Iron ore powder composite agglomeration feeding method and system

Abstract

The present invention discloses a method and system for feeding iron ore powder composite agglomerates. The method includes diverting iron ore powder raw materials according to a first judgment model; using the diverted iron ore powder raw materials for a sintering process and a pelletizing process respectively; diverting raw materials for sintering ingredients; mixing the sintering ingredients according to a first mixing process; drying green balls produced by the pelletizing process and diverting them according to a second judgment model; and using the diverted green balls for the pelletizing process and mixing them according to a second mixing process respectively. The present invention can improve the strength of green balls, avoid the problem of green balls being easily broken during transportation, and avoid the problem of large particles in the returned ore easily damaging the pelletized small balls. At the same time, it further improves the utilization efficiency of the iron ore powder raw materials.

Description

Technical Field

[0001] The invention relates to the technical field of iron ore powder composite agglomeration, and in particular to an iron ore powder composite agglomeration feeding method and system. Background Art

[0002] The composite agglomeration method solves the problem of segregation in ironmaking furnace charges and utilizes difficult-to-process resources. Compared with the sintering method, at the same charge bed height, the composite agglomeration method can significantly improve sintering machine productivity. At the same sintering speed, the composite agglomeration method enables ultra-high charge bed operation, significantly reducing solid fuel consumption and improving product quality. The composite agglomeration process has been successfully applied in numerous steel companies, resolving the technical challenges of utilizing iron-containing resources such as specularite concentrate, iron-bearing dust, and vanadium-titanium magnetite.

[0003] However, in the current production practice, there is still much room for improvement in the quality and production efficiency of composite agglomerate products, which is mainly reflected in three aspects: First, it is difficult for the green balls in the composite agglomerate raw materials to enter the sintering process intact. Because the green balls are not strong, they are easily broken during transportation and distribution. The powder produced by the green ball crushing will seriously deteriorate the air permeability of the sintered mixture. At present, scholars have found that by improving the distribution method, the green ball breakage during the distribution process can be improved to a certain extent, but the above method cannot fundamentally improve the strength of the green balls, nor can it solve the problem of easy breakage during the transportation of green balls; second, large particles in the return ore can easily damage the pellets; third, how to efficiently utilize the iron ore powder raw materials within the steel plant.

[0004] In summary, how to further improve the quality of composite agglomerate products and increase production efficiency is one of the important issues that need to be urgently addressed in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite agglomeration and feeding method and system for iron ore powder to solve the deficiencies in the prior art. The method can improve the strength of green balls, avoid the problem of green balls being easily broken during transportation, and avoid the problem of large particles in the returned ore easily destroying the granulated balls. At the same time, the utilization efficiency of the iron ore powder raw materials is further improved.

[0006] The present invention provides a method for composite agglomeration and feeding of iron ore powder, which comprises:

[0007] Dividing the iron ore powder raw material according to the first determination model; the diverted iron ore powder raw material is used for the sintering process and the pelletizing process respectively;

[0008] Divert the raw materials for sintering batch;

[0009] Mixing the sintering ingredients according to the first mixing step;

[0010] The green balls produced by the pelletizing process are dried and divided according to the second determination model; the divided green balls are used in the pelletizing process and mixed according to the second mixing process.

[0011] In the above-mentioned iron ore powder composite agglomeration and feeding method, optionally, the diverted sintering ingredients are mixed respectively according to the first mixing step and the third mixing step.

[0012] The above-mentioned iron ore powder composite agglomeration and feeding method, wherein, optionally, the sintering ingredients include return ore;

[0013] For the portion of the returned ore that needs to enter the third mixing process after diversion, modified raw materials are added before entering the third mixing process.

[0014] The above-mentioned iron ore powder composite agglomeration and feeding method, wherein, optionally, the first mixing step is to sequentially pass through a primary drum mixer, a secondary drum mixer and a tertiary drum mixer;

[0015] The second mixing process is to sequentially pass through a secondary drum mixer and a tertiary drum mixer;

[0016] The third mixing step is to sequentially pass through a strong mixer and a tertiary drum mixer.

[0017] In the above-mentioned iron ore powder composite agglomeration and feeding method, optionally, the formula corresponding to the first determination model is:

[0018]

[0019] Among them, Y is the comprehensive performance index of iron-containing dust, S k is the average specific surface area of ​​the detected green balls, S min To set the minimum specific surface area for pelletization, D i To detect the average particle size of the green balls, D max To set the maximum average particle size for pelletizing, a and b are both constant coefficients.

[0020] In the above-mentioned iron ore powder composite agglomeration and feeding method, optionally, the formula corresponding to the second determination model is:

[0021]

[0022] Among them, Z is the comprehensive performance index of green balls, W i To detect the moisture content of the green ball, W min To set the minimum moisture content for qualified pelletizing, P i is the detected falling strength of the green ball, P max To set the maximum compressive strength suitable for return pelletizing, D iTo detect the average particle size of the green balls, D max To set the maximum average particle size for pelletizing, a, b and c are all constant coefficients.

[0023] In the iron ore powder composite agglomeration and feeding method as described above, optionally, the green balls produced by the pelletizing process are dried to a moisture content of 1.5% to 2.5%.

[0024] The present invention also provides an iron ore powder composite agglomeration feeding system for use in any of the above methods, wherein the feeding system comprises an iron ore powder screening unit, a pelletizing unit, a sintering batching unit, a mixing unit, and a green ball screening unit;

[0025] The iron ore fines screening unit is used to divert the iron ore fines raw materials according to the first determination model, and transport the diverted iron ore fines raw materials to the pelletizing unit and the sintering batching unit respectively;

[0026] The pelletizing unit is used to make pellets and dry the green pellets;

[0027] The green ball screening unit is used to screen out green balls of appropriate size and to divert the green balls of appropriate size according to the second determination model;

[0028] The mixing unit is used to mix the sintering ingredients mixed by the sintering ingredient unit and receive the diverted green balls at different feeding positions.

[0029] The iron ore fines composite agglomeration and feeding system as described above, wherein, optionally, the mixing unit includes a primary drum mixer, a secondary drum mixer, a tertiary drum mixer and a powerful mixer;

[0030] The outlet of the primary drum mixer is connected to the inlet of the secondary drum mixer via a conveyor belt, and the outlet of the secondary drum mixer is connected to the inlet of the tertiary drum mixer via a conveyor belt; the outlet of the intensive mixer is connected to the inlet of the tertiary drum mixer via a conveyor belt;

[0031] The green ball screening unit is used to screen the green balls into a first sub-stream, a second sub-stream, a third sub-stream, a fourth sub-stream and a fifth sub-stream; the particle size of the green balls in the first sub-stream, the second sub-stream, the third sub-stream, the fourth sub-stream and the fifth sub-stream gradually increases;

[0032] The first split is conveyed to the intensive mixer, the second split is conveyed to the primary drum mixer, the fourth split is conveyed to the tertiary drum mixer, and the fifth split is conveyed to the intensive mixer after being crushed;

[0033] The third split flow is configured to be split again according to the second determination model and transported to the pelletizing unit and the secondary drum mixer, respectively.

[0034] The iron ore powder composite agglomeration and feeding system as described above, optionally, further comprises a modified raw material preparation unit for preparing the modified raw material and conveying the modified raw material to the intensive mixer.

[0035] Compared with the prior art, the present invention diverts the iron ore powder raw material and uses different processes to agglomerate different diversions. Specifically, the iron ore powder raw material is diverted according to the first judgment model to obtain iron ore powder suitable for sintering process and suitable for pelletizing process, which can improve product quality.

[0036] When using the pelletizing process to make blocks, the formed green balls are dried. During the drying process, the capillary water decreases, the capillary shrinks, the capillary force increases, and the bonding force between particles strengthens. Therefore, the strength of the balls gradually increases, which can reduce the breakage of the green balls during transportation.

[0037] The present invention diverts the sintering ingredients, further improving the granulation effect of the composite agglomeration. The present invention diverts the large-particle lump ore and fuel, and then modifies them in a powerful mixer before mixing them, which can effectively prevent the large-particle hard return ore from destroying the granulated balls; after the return ore is diverted, the large-particle lump ore is mixed with the oversized green balls, which can not only crush the oversized green balls, but also use the powder after the green balls are crushed for surface modification; after the dried pellets are crushed, they become iron ore powder and bentonite powder with strong adhesion, which can adhere well to the surface of the large-particle return ore, effectively solving the problem of the difficulty in handling oversized green balls; at the same time, the diverted return ore can further crush the large-particle fuel in the powerful mixer. After the hydrophobic fuel is modified in the powerful mixer, not only the granulation effect is good and it can be evenly distributed into the raw materials, but also the emission of harmful gases can be reduced when the modified fuel is burned. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the steps of the iron ore powder composite agglomeration and feeding method proposed by the present invention;

[0039] Figure 2 This is a structural diagram of the iron ore powder composite agglomeration and feeding system proposed by the present invention;

[0040] Figure 3 This is a schematic diagram of the installation structure of the transition mechanism of the sieve plate proposed by the present invention;

[0041] Figure 4 It is a structural schematic diagram of the roller screen mechanism proposed in the present invention.

[0042] Description of reference numerals:

[0043] 1- Iron ore powder screening unit, 2- Green ball screening unit, 3- Primary drum mixer, 4- Secondary drum mixer, 5- Tertiary drum mixer, 6- Powerful mixer, 7- Iron concentrate trough, 8- Bentonite trough, 9- Disc pelletizer, 10- Green ball conveying mechanism, 11- Ferry mechanism, 12- Roller screen mechanism, 13- Green ball reclassification device, 14- Iron raw material silo, 15- Second fuel silo, 16- First return ore silo, 17- Second quicklime silo, 18- Iron dust silo, 1 9 - Second return ore silo, 20 - First fuel silo, 21 - Fuel crushing device, 22 - Fuel screening mechanism, 23 - First quicklime silo, 24 - Quicklime digestion tank, 25 - Lime milk buffer tank, 26 - Flow control valve, 27 - First hot air hood, 28 - First air inlet, 29 - Air outlet, 30 - Sieve plate, 31 - Rotating shaft, 32 - Jack, 33 - Second hot air hood, 34 - Second air inlet, 35 - Bulk material collection hopper, 36 - Exhaust port, 37 - Return ore screen. DETAILED DESCRIPTION

[0044] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0045] In order to solve the problems raised in the background technology, the present invention proposes the following embodiments to solve the problems.

[0046] Example 1

[0047] Please refer to Figure 1 This embodiment proposes a method for composite agglomeration and feeding of iron ore powder, which includes the following steps:

[0048] S1, diverting the iron ore powder raw material according to the first determination model; the diverted iron ore powder raw material is used for a sintering process and a pelletizing process respectively.

[0049] Specifically, the first judgment model determines whether to use the pelletizing process or the sintering process to make agglomerates based on the particle size of the iron-containing dust. Specifically, the finer the particle size, usually when the iron-containing dust has a particle size of less than 200 mesh accounting for more than 75%, it is suitable for pelletizing; the larger the specific surface area, the more suitable it is for pelletizing process.

[0050] In a specific implementation, the formula corresponding to the first determination model is:

[0051]

[0052] Among them, Y is the comprehensive performance index of iron-containing dust, S k is the average specific surface area of ​​the detected green balls, S min To set the minimum specific surface area for pelletization, D i To detect the average particle size of the green balls, D maxTo set the maximum average particle size for pelletizing, a and b are both constant coefficients.

[0053] The first judgment model can be used to separate raw materials suitable for pelletizing and sintering processes based on the specific surface area and particle size of the green balls. In practice, a preset value for the comprehensive performance of the iron-containing dust can be set. When the calculated comprehensive performance Y of the iron-containing dust is greater than the set value, the iron ore fines are transferred and used for pelletizing. When the calculated comprehensive performance Y of the iron-containing dust is less than the set value, the iron ore fines are transferred and used as a raw material for sintering.

[0054] S2, diverting the raw materials of the sintering batch. In specific implementation, diverting the raw materials of the sintering batch mainly involves diverting the fuel and the return ore.

[0055] For the return ore, in the specific implementation, the return ore involved in sintering can be screened by a vibrating screen and other devices, and the return ore with a particle size greater than 3 mm can be transferred to the first return ore bin to serve as one of the raw materials for sintering ingredients; the return ore with a particle size greater than 3 mm can be transferred to the second return ore bin to be transferred to the high-pressure mixer as return ore.

[0056] For the fuel, it is first fed in a fixed quantity and crushed before being diverted. The diversion process can be achieved through a fuel screen. Specifically, the screen grading particle size is set to 3 mm, and the fuel with a particle size greater than 3 mm is transferred to the first fuel bin to supply the strong mixer; the fuel with a particle size not greater than 3 mm is transferred to the second fuel bin to be used as one of the raw materials for sintering ingredients and transferred to the primary drum mixer.

[0057] The fuel and return ore above 3mm are transferred to a powerful mixer and fully mixed first. During the mixing process of large-particle return ore and fuel, the return ore and fuel are squeezed against each other. The hardness of the return ore is high and the oversized fuel particles can be ground into finer particles.

[0058] During specific implementation, in order to prevent large particles of return ore from destroying the already granulated green balls during the granulation process, a modified raw material is added to part of the return ore that needs to enter the third mixing process after diversion before entering the third mixing process. That is, the modified raw material is added before the return ore is added to the intensive mixer, or the modified raw material, return ore and fuel are added to the intensive mixer. Specifically, the modified raw material is lime milk. During the mixing process, the surface of the return ore and fuel particles is further eroded, and the specific surface area is increased, which is beneficial to the modification of the lime milk. The lime milk performs surface modification on the return ore and fuel solid particles with strong hydrophobicity, thereby improving the hydrophilicity of the surface of the solid particles.

[0059] The specific modification process for return ore and fuel is as follows: The extremely viscous lime milk produced by excessive digestion of quicklime modifies the surface of large, hydrophobic return ore and fuel particles. The modified large return ore particles are then thoroughly mixed with the sticky pellet adhesion powder. The large return ore particles are granulated so that a layer of powder particles adheres to their surface, forming a buffer layer that effectively reduces the hardness of the return ore particles and reduces the sharp corners on the particle surface. In this way, the large return ore particles will not damage the already granulated pellets during the granulation process. Since composite agglomeration has an additional three mixing steps compared to ordinary sintering, the mixing time is increased. Large return ore particles can easily damage the structure of the already granulated particles and pellets during the mixing process. This phenomenon can be reduced by diversion. Note that lime milk modified fuel can also reduce harmful gas emissions. Because sulfur oxides and nitrogen oxides in the sintering process are mainly caused by fuel combustion, coating the fuel with a layer of lime can absorb some of the harmful gases.

[0060] S3, mixing the sintering ingredients according to the first mixing step;

[0061] In a specific implementation, the first mixing step is to sequentially mix the raw materials in a primary drum mixer, a secondary drum mixer and a tertiary drum mixer. In a specific implementation, the sintering ingredients include raw materials including iron raw materials, fuel, return ore, quicklime and iron ore powder.

[0062] S4, drying the green balls produced by the pelletizing process and dividing them according to the second determination model; the divided green balls are used in the pelletizing process and mixed according to the second mixing step.

[0063] Specifically, the second mixing step involves mixing in a secondary drum mixer and a tertiary drum mixer, respectively. In practice, the second determination model makes a comprehensive judgment based on factors such as average particle size, moisture content, and drop strength. Specifically, the smaller the average particle size, the more suitable it is for pelletizing, as larger particles are more likely to exceed 14 mm after pelletizing.

[0064] When drying the green pellets produced in the pelletizing process, hot exhaust gas from the ring cooler can be used to dry the green pellets at a temperature of 100 to 180 degrees Celsius, preferably around 140 degrees Celsius. After drying, the moisture content of the green pellets is preferably reduced to 1.5% to 2.5%.

[0065] In practice, the pellets are first sieved according to their size into different fractions: less than 1 mm, 1-3 mm, 3-8 mm, 8-14 mm, and greater than 14 mm. Pellets in the 3-8 mm fraction are considered appropriately sized. A second determination model then separates the pellets in the 3-8 mm fraction. These pellets then have two treatment paths: one is transferred to the pelletizing feed for re-pelletization; the other is transferred to a secondary drum mixer for mixing and pelletizing.

[0066] In specific implementation, the formula corresponding to the second determination model is:

[0067]

[0068] Among them, Z is the comprehensive performance index of green balls, W i To detect the moisture content of the green ball, W min To set the minimum moisture content for qualified pelletizing, P i is the detected falling strength of the green ball, P max To set the maximum compressive strength suitable for return pelletizing, D i To detect the average particle size of the green balls, D max To set the maximum average particle size for pelletizing, a, b and c are all constant coefficients.

[0069] The second judgment model can use parameters such as average particle size, moisture content, and drop strength to determine whether the pellets need to be returned to pelletizing. Specifically, a threshold can be pre-set. When the calculated comprehensive performance index Z of the green pellets is greater than the set threshold, the pelletizing process is restarted. When the calculated comprehensive performance index Z of the green pellets is not greater than the set threshold, the pellets are transferred to a secondary drum mixer. In other words, the greater the moisture content, the weaker the pellets' strength; and when returned to pelletizing, the pellets are more likely to adhere to fine particles and grow, making them more suitable for return to pelletizing. The lower the compressive strength of the green pellets, the more suitable they are for return to pelletizing. This is because the longer the pressing time of the green pellets returned to pelletizing, the higher their strength. If they are directly sent to a secondary drum mixer, they are easily crushed into fine powder by compression. Green pellets with lower strength can adhere to the pellets even if they are crushed into fine powder when returned to pelletizing. However, if green pellets with lower strength are crushed into powder in a secondary drum mixer, their particle size is finer than that of the sintering raw materials, which will seriously deteriorate the permeability of the sintering material layer.

[0070] It should be pointed out that the above-mentioned S1, S2, S3 and S4 are only used to distinguish different steps, and do not limit the order of the steps.

[0071] In a specific implementation, the divided sintering ingredients are mixed in a first mixing step and a third mixing step respectively. The third mixing step is to sequentially pass through a strong mixer and a tertiary drum mixer.

[0072] Example 2

[0073] Please refer to Figures 2 to 4 This embodiment proposes an iron ore powder composite agglomeration feeding system. This system is used to implement the method described in Example 1, wherein the feeding system includes an iron ore powder screening unit 1, a pelletizing unit, a sintering batching unit, a mixing unit, and a green ball screening unit 2;

[0074] The iron ore fines screening unit 1 is used to divert the iron ore fines raw materials according to the first determination model, and transport the diverted iron ore fines raw materials to the pelletizing unit and the sintering batching unit respectively.

[0075] The pelletizing unit is used to make pellets and dry the green pellets.

[0076] The green ball screening unit 2 is used to screen out green balls of appropriate size and to divert the green balls of appropriate size according to the second determination model.

[0077] The mixing unit is used to mix the sintering ingredients mixed by the sintering ingredient unit and receive the diverted green balls at different feeding positions.

[0078] More specifically, the mixing unit includes a primary drum mixer 3, a secondary drum mixer 4, a tertiary drum mixer 5, and an intensive mixer 6. The outlet of the primary drum mixer 3 is connected to the inlet of the secondary drum mixer 4 via a conveyor belt, the outlet of the secondary drum mixer 4 is connected to the inlet of the tertiary drum mixer 5 via a conveyor belt; and the outlet of the intensive mixer 6 is connected to the inlet of the tertiary drum mixer 5 via a conveyor belt.

[0079] In specific implementations, different mixing processes can be achieved depending on the location where the materials are fed. For example, when the materials are fed to the inlet of the primary drum mixer 3, the materials will sequentially pass through the primary drum mixer 3, the secondary drum mixer 4, and the tertiary drum mixer 5, i.e., the first mixing process described in Example 1; when the materials are fed to the inlet of the secondary drum mixer 4, the materials will sequentially pass through the secondary drum mixer 4 and the tertiary drum mixer 5, i.e., the second mixing process described in Example 1; when the materials are fed to the inlet of the intensive mixer 6, the materials will sequentially pass through the intensive mixer 6 and the tertiary drum mixer 5, i.e., the third mixing process described in Example 1.

[0080] In a specific implementation, the green ball screening unit 2 is used to screen the green balls into a first stream, a second stream, a third stream, a fourth stream, and a fifth stream; the particle size of the green balls in the first stream, the second stream, the third stream, the fourth stream, and the fifth stream gradually increases. In a specific implementation, the particle size of the first stream is no greater than 1 mm, the particle size of the second stream is 1 to 3 mm, the particle size of the third stream is 3 to 8 mm, the particle size of the fourth stream is 8 to 14 mm, and the particle size of the fifth stream is greater than 14 mm.

[0081] The first sub-stream is conveyed to the intensive mixer 6 , the second sub-stream is conveyed to the primary drum mixer 3 , the fourth sub-stream is conveyed to the tertiary drum mixer 5 , and the fifth sub-stream is conveyed to the intensive mixer 6 after being crushed.

[0082] The third split flow is configured to be split again according to the second determination model and transported to the pelletizing unit and the secondary drum mixer 4 respectively.

[0083] During specific implementation, a modified raw material preparation unit is further included, which is used to prepare the modified raw material and transport the modified raw material to the intensive mixer 6 .

[0084] In order to clearly explain the structure of this system, different functions are described below.

[0085] The iron ore fines screening unit 1 is used to separate the iron ore fines. Part of the separated iron ore fines enters the pelletizing unit, and the other part enters the sintering batching unit.

[0086] The pelletizing unit includes an iron ore concentrate trough 7, a bentonite trough 8, a disc pelletizer 9, and a green pellet conveyor 10. The iron ore concentrate trough 7 is connected to the iron ore fines screening unit 1 and is used to collect a portion of the diverted iron ore fines and convey them to the disc pelletizer 9. The bentonite trough 8 is used to hold bentonite and convey it to the disc pelletizer 9. The disc pelletizer 9 produces green pellets. The green pellet conveyor 10 is used to transport the green pellets and perform preliminary drying on them.

[0087] The green ball screening unit 2 includes a transition mechanism 11, a roller screening mechanism 12, and a green ball re-dividing device 13. The transition mechanism 11 is arranged between the green ball conveying mechanism 10 and the roller screening mechanism 12. The transition mechanism 11 is used to perform secondary drying of the green balls and perform preliminary screening, that is, to screen out green balls with a particle size of less than 1 mm, which is also the first split. The roller screening mechanism 12 is used to screen out the second split, the third split, the fourth split, and the fifth split. The first split is conveyed to the intensive mixer 6, the second split is conveyed to the primary drum mixer 3, and the third split is conveyed to the green ball re-dividing device 13. The green ball re-dividing device 13 is to further divert the third split according to the second judgment model. The fourth split is conveyed to the tertiary drum mixer 5, and the fifth split is conveyed to the intensive mixer 6. The green ball reclassification device 13 transports the green balls suitable for ball making back to the disc ball making machine 9 according to the second judgment model. Although the green balls re-conveyed to the disc ball making machine 9 have suitable particle size, their water content is relatively high and the green ball strength is low, which makes them easy to break in the subsequent process. The green ball reclassification device 13 transports the green balls suitable for sintering to the secondary drum mixer 4 for mixing and granulation according to the second judgment model.

[0088] The sintering batching unit includes an iron raw material bin 14, a second fuel bin 15, a first return ore bin 16, a second quicklime bin 17, and an iron-containing dust bin 18. The iron raw material bin 14, the second fuel bin 15, the first return ore bin 16, the second quicklime bin 17, and the iron-containing dust bin 18 are used to feed the primary drum mixer 3.

[0089] The return ore screen 37 is used to screen the return ore and transport the screened return ore to the first return ore bin 16 and the second return ore bin 19. The material in the second return ore bin 19 is used to be transported to the intensive mixer 6.

[0090] The fuel processing unit includes a first fuel silo 20, a fuel crushing device 21, and a fuel screening mechanism 22. Fuel from the first fuel silo 20 is delivered to the fuel crushing device 21 for crushing, then screened by the fuel screening mechanism 22. A portion of the screened fuel is delivered to the second fuel silo 15, and the remaining portion is delivered to the intensive mixer 6.

[0091] The mixing unit includes the aforementioned primary drum mixer 3, secondary drum mixer 4, tertiary drum mixer 5 and intensive mixer 6, and the connection structure thereof is the same as that described above, and thus will not be repeated.

[0092] The modified raw material is prepared by the modified raw material preparation unit, which includes a first quicklime silo 23, a quicklime slurry tank 24, a lime milk buffer tank 25, and a flow control valve 26. The first quicklime silo 23, the quicklime slurry tank 24, the lime milk buffer tank 25, and the flow control valve 26 are sequentially connected to facilitate delivery to the intensive mixer 6 at a set rate. Specifically, the quicklime in the first quicklime silo 23 is fed into the quicklime slurry tank 24 for slurrying. After slurrying, it is piped into the lime milk buffer tank 25, which is then piped into the intensive mixer 6. A flow control valve 26 on the pipe entering the intensive mixer 6 controls the amount of lime milk added.

[0093] It should be noted that a first hot air hood 27 is located above the green pellet conveying mechanism 10. The hot air within this hood is drawn from the low-temperature hot exhaust gas from the annular cooler, reaching a temperature of approximately 140°C. In practice, however, this air can be drawn from other sources, as long as the temperature is between 100°C and 180°C. Specifically, the first hot air hood 27 includes a first air inlet 28 and multiple air outlets 29 at different locations. By controlling the position of the air outlets 29 of the first hot air hood 27 and adjusting the hot exhaust gas flow rate and temperature, the moisture content of the green pellets after drying in the first hot air hood 27 is reduced to between 4% and 5%. In some implementations, an electric heating device can be used in place of the first hot air hood 27 and the corresponding piping.

[0094] Please refer to Figure 3The transition mechanism 11 includes a sieve plate 30, one side of the sieve plate 30 is rotatably connected to the bracket through a rotating shaft 31, the rotating shaft 31 is arranged horizontally, and the sieve plate 30 is inclined and tilted downward in a direction away from the rotating shaft 31, and the bottom of the opposite side of the sieve plate 30 is movably overlapped on the jack 32; holes are distributed on the sieve plate 30, and the aperture of the holes is 1mm; a second hot air hood 33 is provided above the sieve plate 30, and a second air inlet 34 is provided above the second hot air hood 33. The second hot air hood 33 is trumpet-shaped, and the second Hot air from the secondary air inlet 34 is blown onto the pellets on the sieve plate 30 through the open bottom opening, further drying the pellets and reducing their moisture content to 1.5%-2.5%. A bulk material collection hopper 35 is located at the bottom of the sieve plate 30, with an exhaust port 36 formed in it. This exhaust port 36 removes the hot air from above the rotating sieve plate 30. This exhaust creates a slight negative pressure within the hopper 35, allowing fine powder that falls from the pellets on the sieve plate 30 to fall smoothly into the hopper 35. The pellets are then fed through the sieve plate 30 onto the roller screening mechanism 12, which has three roller spacings: 3mm near the transition mechanism 11, 8mm in the middle, and 14mm at the end. After passing through the roller screening mechanism 12, the pellets are sorted into four different size fractions: 1-3mm; 3-8mm; 8-14mm; and larger than 14mm.

[0095] Through the above embodiment 1 and embodiment 2, the present invention has at least the following effects:

[0096] 1. The present invention first preliminarily dries the green balls and then mixes them with the raw materials after sintering and granulation. The strength of the green balls after drying is greatly improved, which can effectively prevent the green balls and the sintered mixed materials from breaking during mixing and subsequent distribution in the sintering machine. The present invention also provides a specific drying method in combination with the process configuration; that is, drying in two steps: first, a first-stage drying is performed through the first hot air hood 27 to preliminarily adjust the moisture content of the green balls to 4%-5%; after the green balls are dried, the strength is improved, and they continue to enter the transition mechanism 11 for a second-stage drying to further reduce the moisture content to 1.5%-2.5%, further improving the strength of the pellets. During the thermal drying process, the moisture on the surface of the green balls is relatively easy to remove, but the moisture inside is difficult to remove. When the moisture content of the green balls is reduced to 1.5%-2.5%, the strength is already high, and it is difficult to further reduce the moisture content. In the present invention, the moisture content of the green balls is reduced to, and at the same time, the green balls can be further squeezed tightly to improve their own strength during the rolling process on the rotating screen plate 30. The strength of the green balls after one stage of drying is low, so static drying is performed on a belt conveyor; after one stage of drying, the strength of the green balls is improved, and dynamic drying can be performed on a rotating screen plate 30 to further improve the strength. Specifically, the moisture content of the green balls after drying is best at 1.5%-2.5%.

[0097] The change in green ball strength during the drying process is due to the fact that green balls primarily rely on capillary water to bond the particles together, giving them a certain strength. As the drying process progresses, the capillary water content decreases, the capillaries contract, the capillary forces increase, and the interparticle bonding strengthens, thus gradually increasing the ball's strength. After most of the capillary water has been removed, isolated, interconnected rings of water remain at the particle contact points. This is known as contact-state capillary water. This is when the bonding force is at its highest, resulting in the highest ball strength. As the water content decreases further, the capillary water disappears, and the ball's strength decreases due to the loss of capillary bonding. At the moment of loss of weakly bound water, the particles move closer together, and molecular forces increase the interparticle bonding, further increasing the ball's strength. The present invention regulates the green ball moisture content to 1.5%-2.5%, essentially keeping the green ball moisture close to that of contact-state capillary water. This not only increases green ball strength but also makes drying easier.

[0098] Second, the present invention diverts the return ore and fuel, further improving the granulation effect of the composite agglomeration. The present invention diverts the large-particle lump ore and fuel, and then modifies them in the powerful mixer 6 before mixing them, which can effectively prevent the large-particle hard return ore from destroying the granulated balls; after the return ore is diverted, the large-particle lump ore is mixed with the oversized green balls (particle size greater than 14mm), which not only crushes the oversized green balls, but also uses the powder after the green balls are crushed for surface modification. After the green balls are dried and crushed, they become iron ore powder and bentonite powder with strong adhesion, which can adhere well to the surface of the large-particle return ore, effectively solving the problem of the difficulty in handling oversized green balls; at the same time, the diverted return ore can further crush the large-particle fuel in the powerful mixer 6. After the hydrophobic fuel is modified in the powerful mixer 6, not only the granulation effect is good and it can be evenly distributed into the raw materials, but also the emission of harmful gases can be reduced when the modified fuel is burned.

[0099] 3. Compared with existing composite agglomeration processes, this invention processes the raw balls produced by the disc and then mixes them with sintering raw materials at different stages according to the properties of the raw balls. This not only improves the composite agglomeration and granulation effect, but also effectively increases the strength of the granulated balls. Specifically, the present invention performs two-stage drying on the raw balls and then conducts diversion processing based on the properties of the raw balls; fine powder within 1mm is used to participate in the modification of the returned ore; 1-3mm raw balls enter the primary drum mixer 3 for mixing; 3-8mm raw balls are judged by the judgment model P2 and have two processing paths: one can be transferred to the secondary drum mixer 4 for granulation, and the other can be transferred and then distributed to the disc pelletizer 9 for pelletizing. 8-14mm raw balls are transferred to the tertiary drum mixer 5 for mixing.

[0100] Fourth, the present invention also achieves the problem of efficient utilization of fine iron ore powder within steel plants. After the fine iron ore powder raw materials are collected, the particle size composition and specific surface area analysis can be used to determine whether they are suitable for pelletizing or sintering, thus achieving the rational utilization of fine iron-containing dust.

[0101] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the scope of implementation of the present invention is not limited to what is shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present invention.

Claims

1. A method for composite agglomeration and feeding of iron ore powder, characterized by: include, Diverting the iron ore fines raw material according to the first determination model; The separated iron ore fines are used in sintering and pelletizing processes respectively; Divert the raw materials for sintering batch; Mixing the sintering ingredients according to the first mixing step; Drying the green balls produced by the pelletizing process and dividing them according to the second determination model; using the divided green balls in the pelletizing process and mixing them according to the second mixing step; The raw materials for sintering batching include fuel and return ore. The return ore with a particle size of no more than 3 mm is transported to the first return ore bin and used as one of the raw materials for sintering batching. The return ore with a particle size of more than 3 mm is transported to the second return ore bin and transported to the intensive mixer as return ore. The fuel with a particle size of more than 3 mm is transported to the intensive mixer, and the fuel with a particle size of no more than 3 mm is transported to the second fuel bin and transported to the primary drum mixer as one of the raw materials for sintering batching. The divided sintering ingredients are mixed according to the first mixing step and the third mixing step respectively; The sintering ingredients include return ore; For the portion of the returned ore that needs to enter the third mixing process after diversion, adding modified raw materials before entering the third mixing process; The first mixing process is to sequentially pass through a primary drum mixer, a secondary drum mixer and a tertiary drum mixer; The second mixing process is to sequentially pass through a secondary drum mixer and a tertiary drum mixer; The third mixing step is to sequentially pass through a strong mixer and a tertiary drum mixer.

2. The iron ore powder composite agglomeration and feeding method according to claim 1, characterized in that: The green pellets produced by the pelletizing process are dried to a moisture content of 1.5% to 2.5%.

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