Sintering method for reducing consumption and reducing CO content of flue gas

Abstract

The invention relates to a sintering method for reducing consumption and CO content in flue gas, which comprises the steps of primary screening of fuel, secondary screening of fuel, screening of iron ore charge, primary mixing of small particle size, primary mixing of large particle size, secondary mixing and subsequent sintering, and is characterized in that the fuel and the iron ore are screened, and the fuel with specific particle size and the iron ore charge with specific particle size are respectively and primarily mixed; the method comprises the following steps of: firstly, performing secondary mixing and charging on relatively small materials, performing secondary mixing for a certain time, then charging relatively large materials, and continuously performing secondary mixing, so that the particle size of the sintered ore is relatively uniform, a relatively large amount of fuel can be obtained from the upper layer during sintering, and the effects of reducing consumption and reducing the content of carbon monoxide in flue gas are realized by matching with the setting of a subsequent sintering process.

Description

Technical Field

[0001] The invention relates to the technical field of sintering ore, and in particular to a sintering method for reducing consumption and CO content in flue gas. Background Art

[0002] Sintered ore is the main raw material for blast furnace ironmaking, so sintering is a very important step in raw material processing before the blast furnace ironmaking process. After the iron ore, iron concentrate, fuel and flux are mixed and granulated under the action of water, they are sintered into blocks through a series of physical and chemical changes on the sintering table to complete the sintering. In the existing sintering process, hot air negative pressure sintering is generally adopted. By blowing air downward from the top of the material layer, and setting negative pressure at the bottom of the material layer, the hot air can pass through the pores inside the material layer and fully contact the material, thereby strengthening the sintering process. In this process, due to the trend of thicker and thicker material layers, the importance of the air permeability of the material layer gradually becomes prominent. If the air permeability deteriorates, not only the sintering effect deteriorates, but also due to insufficient combustion, the carbon monoxide content in the flue gas is also increased, and the solid consumption is also increased.

[0003] At the same time, with the increasing environmental protection requirements, the research on solid consumption and flue gas control in the sintering process is also gradually receiving attention. In the prior art, there is a method of using hydrogen-rich injection to replace part of the carbonaceous raw materials with hydrogen. This setting not only reduces solid consumption, but also reduces the content of carbon-containing gas in the flue gas. However, this setting has limited effect on reducing solid consumption and reducing the carbon monoxide content in the flue gas. If the permeability of the material layer can be further enhanced and the full contact between the hot air and the material layer can be enhanced, incomplete combustion will be greatly reduced, thereby further greatly reducing the carbon monoxide content in the flue gas, and also reducing solid consumption.

[0004] Chinese invention patent publication CN115261615B discloses a sintering batching method for returning ore graded and layered fabrics, which improves air permeability by specifically processing the returning ore, but the improvement effect is limited. Summary of the invention

[0005] The purpose of the present invention is to provide a thick layer sintering method.

[0006] The specific implementation is through the following technical solutions:

[0007] A sintering method for reducing consumption and CO content in flue gas comprises the following steps:

[0008] (1) Primary screening of fuel: The fuel is passed through 3 mm, 1 mm and 0.5 mm vibrating screens in sequence to obtain fuel larger than 3 mm, fuel of 1 to 3 mm, fuel of 0.5 to 1 mm and fuel smaller than 0.5 mm, respectively.

[0009] (2) Secondary screening of fuel: the fuel with a particle size larger than 3 mm obtained by screening in step (1) is placed in a crusher for crushing, and then the fuel obtained after crushing is passed through 3 mm, 1 mm and 0.5 mm vibrating screens in sequence, and the fuel with a particle size larger than 3 mm is returned to the crusher for further crushing, and the 1-3 mm fuel obtained by screening is mixed with the 1-3 mm fuel obtained by step (1) to obtain a medium particle size fuel, the 0.5-1 mm fuel obtained by screening is mixed with the 0.5-1 mm fuel obtained by step (1) to obtain a small particle size fuel, and the fuel with a particle size smaller than 0.5 mm obtained by screening is mixed with the fuel with a particle size smaller than 0.5 mm obtained by step (1) to obtain a fine particle size fuel.

[0010] (3) Screening of iron ore: The iron ore is screened through 3 mm and 0.5 mm vibrating screens to obtain large-size ore with a particle size greater than 3 mm, medium-size ore with a particle size of 0.5 to 3 mm, and small-size ore with a particle size less than 0.5 mm.

[0011] (4) Small particle size primary mixing: 40 to 50 parts by weight of the medium particle size ore obtained in step (3), 2 to 6 parts by weight of iron ore concentrate, 1.2 to 2.3 parts by weight of the small particle size fuel obtained in step (2) and 3 to 8 parts by weight of flux are placed in a mixer, and 1 to 2 parts by weight of water are sprayed into the mixer for primary mixing. The mixing time is 2 to 4 minutes to obtain a small particle size primary mixture.

[0012] (5) Large particle size single mixing: 40-50 weight parts of the large particle size ore obtained in step (3), 2-6 weight parts of the small particle size ore obtained in step (3), 1.3-2.5 weight parts of the medium particle size fuel obtained in step (2) and 3.5-9 weight parts of flux are placed in a mixer, and 1-2 weight parts of water are sprayed into the mixer for single mixing. The mixing time is 2-4 minutes to obtain a large particle size single mixture.

[0013] (6) Second mixing: the small-size mixed material obtained in step (4) is placed in a granulator for second mixing and granulation, and 1.5 to 3 parts by weight of water is sprayed into the granulator at the same time. The granulation time is 1 to 2 minutes. Then, the large-size mixed material obtained in step (5) is placed in the granulator, and 1.2 to 2.5 parts by weight of water is sprayed into the granulator. The granulation is continued for 1 to 2 minutes to obtain second mixing balls.

[0014] As a preference, it also includes:

[0015] (7) Sintering material distribution: Sintered return ore with a particle size or equivalent particle size greater than 10 mm is spread on the sintering trolley as a base material, and the thickness of the base material is 33 to 50 mm. Then, the two mixed balls obtained in step (6) are spread on the top of the base material by a nine-roller spreading device.

[0016] (8) Hydrogen-rich sintering: A plurality of rows of hydrogen nozzles are arranged on the top of the sintering material bed and directed toward the material bed. The hydrogen nozzles are arranged between the ignition point and the midpoint of the material bed, and the distance from the ignition point to the midpoint of the material bed is divided into three equal parts: the section closest to the ignition point is section A, the middle section is section B, and the section closest to the midpoint of the material bed is section C. The number of hydrogen nozzles arranged in section A: the number of hydrogen nozzles arranged in section B: the number of hydrogen nozzles arranged in section C is (2.5-3.5): (1.5-2.5): (0.5-1.5). While the material bed is moving, the material is continuously distributed in the manner of step (7), and ignition is simultaneously performed for sintering. Hot air is blown downward from the top of the sintering material bed, and negative pressure is set at the bottom of the sintering material bed. The volume concentration of hydrogen spraying is 0.61-0.98%, and the sintering speed is controlled to be 21.02-26.2 mm / min.

[0017] (9) Flue gas circulation: A first smoke exhaust port, a second smoke exhaust port and a third smoke exhaust port are provided on the lower side of the material bed, wherein the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port are arranged in sequence from top to bottom in terms of height. Flue gas discharged from the bottom of the sintering material bed after negative pressure sintering is discharged through the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port, wherein the outlet of the second smoke exhaust port is connected to the externally arranged desulfurization, denitrification treatment and carbon monoxide catalytic adsorption components through a pipeline for discharge, and the first smoke exhaust port and the third smoke exhaust port are connected to the flue gas recycling hood through a pipeline.

[0018] (10) Flue gas recycling: A flue gas recycling hood is arranged on the side of the sealing hood above the sintering material layer. An upper smoke inlet and a lower smoke inlet are arranged at the inlet end of the flue gas recycling hood. The upper smoke inlet is connected to the third smoke exhaust port through a pipe, and the lower smoke inlet is connected to the first smoke exhaust port through a pipe. A plurality of arc-shaped guide plates with their terminals arced downward are arranged at the outlet end of the flue gas recycling hood. The terminals of the arc-shaped guide plates extend beyond the outlet end of the flue gas recycling hood, and the diameter of the outlet end of the flue gas recycling hood is equal to or greater than 100 mm. The effective diameter is greater than the diameter of the inlet end of the smoke recycling hood or an equivalent diameter. The smoke exhausted through the first smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the lower smoke inlet. The smoke exhausted through the third smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the upper smoke inlet. After the recycled smoke is remixed in the smoke recycling hood, it is discharged into the top of the sintering material layer in the sealing hood through the plurality of arc-shaped guide plates, and the recycled smoke re-enters the sintering material layer.

[0019] Preferably, the starting end of the arc-shaped guide plate of the flue gas recycling hood is arranged inside the flue gas recycling hood, and the terminal end of the arc-shaped guide plate faces the sealing hood and exceeds the outlet end of the oxygen recycling hood; the arc-shaped guide plate of the flue gas recycling hood includes an upper guide plate and a lower guide plate, wherein one or two lower guide plates are provided, and more than two upper guide plates are provided, and the distances between the starting ends of adjacent upper guide plates are equal or substantially equal, and the distance between the terminal ends of adjacent upper guide plates is greater than the distance between the starting ends of the two adjacent upper guide plates.

[0020] Preferably, the radius of the arc-shaped upper guide plate decreases sequentially from top to bottom, and the radius of the arc-shaped lower guide plate is greater than the radius of the arc-shaped guide plate above the lower guide plate.

[0021] Preferably, the diameter or equivalent diameter of the outlet end of the flue gas recycling hood is D2, and the diameter or equivalent diameter of the inlet end of the flue gas recycling hood is D1, satisfying 1.32≤D2 / D1≤1.65.

[0022] Preferably, the height of the first smoke exhaust port is h1, the height of the second smoke exhaust port is h2, and the height of the third smoke exhaust port is h3, satisfying h2>h1>h3.

[0023] Preferably, in step (3), the iron ore material is a foreign ore (eg, Australian ore, South African ore, Brazilian ore, Ukrainian ore, Russian ore, Kazakhstan ore and / or Indian ore, etc.).

[0024] Preferably, the fuel is coke powder and anthracite powder, and the weight ratio of coke powder to anthracite powder is (70-80):(20-30), and the anthracite powder has an ignition temperature of 450-550°C.

[0025] Preferably, the anthracite powder is anthracite powder having an ash content of 8 to 15 wt.% and an ignition temperature of 450 to 550°C.

[0026] Preferably, the first smoke exhaust port and the third smoke exhaust port are also connected to the oxygen-enriched air exhaust port through a pipe, and the oxygen-enriched air exhaust port discharges oxygen-enriched air with an oxygen volume content of 23-31% into the pipe connected to the first smoke exhaust port and the third smoke exhaust port.

[0027] Preferably, the particle size fuel obtained in step (2) is ground to less than 200 meshes by a coal mill and then sent to the blast furnace coal injection system as a coal injection raw material.

[0028] Preferably, the flux is a mixture of 75-85 wt.% quicklime and 15-25 wt.% dolomite.

[0029] Preferably, the crusher in step (2) is a four-roll crusher, and the roller spacing of the upper rollers of the four-roll crusher is 7.5-8.5 mm, and the roller spacing of the lower rollers is 3.5-5.5 mm.

[0030] The technical effects of the present invention are:

[0031] (1) The present invention screens the fuel by particle size, screens the iron ore by particle size, mixes the iron ores of different specific particle sizes with the fuels of different specific particle sizes, and adds the materials twice during the second mixing. First, the mixture formed by the medium-sized iron ore is granulated for a certain period of time, and then the mixture formed by the large-sized iron ore is added, so that in the first second mixing process, the medium-sized iron ore is used as the core to form a certain particle size and then continue the large-sized nucleation and growth process (that is, the relatively small-sized iron ore is mixed for a relatively long time), so that the materials formed after the second mixing are basically in the particle size range of 5 to 5.5 mm, so that the permeability of the material layer during sintering is greatly improved, and the problem of small-sized materials filling the gaps between large-sized materials due to the difference in particle size of the materials is avoided. The overall permeability is greatly improved, which greatly reduces the phenomenon of incomplete combustion, thereby reducing the solid consumption and the content of carbon monoxide in the flue gas.

[0032] (2) By mixing medium-sized ore, iron ore concentrate and small-sized fuel as the main body of the second-mixed material, since the second-mixing cycle of this part of the material is long and the iron ore concentrate particle size is small, relatively more fuel can be bonded to the surface of the medium-sized ore, and the outer layer fuel accounts for a relatively large proportion, so that the density of this part of the material is lower than that of the large-sized ore. When the nine-roller feeding device is used for feeding, the material with the same particle size and larger density is relatively less affected by the roller gap and falls relatively first, so that the medium-sized ore and the material with more surface fuel are distributed in the upper layer during the segregation feeding, resulting in more fuel in the upper layer than in the lower layer, thereby strengthening the surface heat development. When the surface heat develops and the fuel is fully burned, the overall permeability of the ore layer will be improved. With good permeability, the contact between gas and material is more complete, and complete combustion controls the CO content in the flue gas.

[0033] (3) The present invention arranges a specific front-end enhanced hydrogen-rich injection, and after ignition, the hot air fully injects hydrogen in the upper stage, further supplements the surface heat development, and strengthens the heat distribution on the upper material. When the same amount of heat is obtained, the reaction of the carbonaceous raw material is reduced to a certain extent, thereby reducing the carbon monoxide content in the flue gas from the source, and using hydrogen to enhance combustion instead of carbonaceous raw materials, which also reduces solid consumption.

[0034] (4) The present invention reuses the flue gas after specific distribution and supplementation with a certain amount of oxygen-enriched air. The reuse of the flue gas not only brings the heat of the flue gas back into the sintering material layer to recover a certain amount of energy, but more importantly, returns the CO that is not fully burned in the flue gas to the material layer and fully burns it through a combustion reaction with oxygen, thereby greatly reducing the carbon monoxide content in the flue gas. By using carbon monoxide and hydrogen as part of the fuel, solid consumption is inevitably reduced.

[0035] (5) The present invention divides the flue gas into three layers when it is discharged. Although the flue gas is not clearly classified, the upper layer is mainly composed of lighter flue gas (such as carbon monoxide), the lower layer is mainly composed of flue gas carrying a lot of particulate matter, and the middle layer is mainly composed of flue gas with carbon dioxide as the main component. Therefore, by discharging the flue gas in the middle layer (since it is recycled, this part of the flue gas has been recycled many times), the emission of particulate matter and carbon monoxide is relatively reduced. By recycling the flue gas in the upper and bottom layers respectively, the carbon monoxide that accounts for a large proportion can be re-burned and converted into carbon dioxide, and the particulate matter in it further contacts the material layer and returns to the material layer, thereby relatively reducing the emission of carbon monoxide and particulate matter. Then, by discharging the upper layer into the smoke exhausted from the third smoke exhaust port and the lower layer into the smoke exhausted from the first smoke exhaust port in the recycling hood, it is achieved that the upper density is relatively high and the lower density is relatively low during the discharge process into the recycling hood. Therefore, due to the relationship between gravity and heat, the smoke can be remixed more fully in the recycling hood, so that it can be evenly contacted with the material layer when the smoke is recycled and re-contacts the material layer.

[0036] (6) Due to the setting of the existing flue gas recycling hood, the flue gas has a certain flow rate. After being discharged into the material layer through the recycling hood, the flue gas is concentrated on the upper part of the material layer on one side of the principle recycling hood, resulting in insufficient contact between the material layer and the recycled flue gas. The present invention first sets the diameter of the inlet end of the recycling hood to be smaller than the diameter of the outlet end, which reduces the gas flow rate to a certain extent, and then sets a guide plate at the outlet end of the flue gas recycling hood, and sets the outlet end of the guide plate beyond the outlet end of the recycling hood, so that the flue gas can flow in the direction of the guide plate; by setting the guide plates to be narrow at the inlet and wide at the outlet, the gas flow rate is further reduced, and when the overall flow rate is reduced, the upper guide plate is set to an arc-shaped structure with the terminal end downward, and the arc is larger as it is closer to the bottom, so that after the flue gas is ejected, it flows obliquely downward to a certain extent along the guide plate with the arc structure, and further diverts the flow, thereby realizing the diversion flow of the flue gas in various parts, and by setting the lower guide plate and setting its arc to a small arc relative to the upper guide plate, it is avoided that the upper area of ​​the material layer near the outlet end of the recycling hood forms a certain turbulence, which further promotes the relative uniformity of the gas of the flue gas recycling part in the upper part of the material layer, thereby enhancing the effect of flue gas recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the arrangement of the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port of the present invention.

[0038] Figure 2 It is a schematic structural diagram of a partial cross-section of the flue gas recycling hood of the present invention.

[0039] Wherein: 101-first smoke exhaust port, 102-second smoke exhaust port, 103-third smoke exhaust port, h1-height of the first smoke exhaust port, h2-height of the second smoke exhaust port, h3-height of the third smoke exhaust port;

[0040] 201-sealing hood, 202-smoke recycling hood, 221-upper smoke inlet, 222-lower smoke inlet, 223-smoke recycling hood outlet, 224-upper guide plate, 225-lower guide plate, 203-sintering material layer, D1-diameter of the inlet end of the smoke recycling hood, D2-diameter of the outlet end of the smoke recycling hood. DETAILED DESCRIPTION

[0041] The process technology scheme of the present invention is further described below by combining embodiments and drawings. Specific embodiments Unless otherwise described, each feature is only an example of a series of equivalent or similar features. It is only to help understand the present invention. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0042] Example 1

[0043] This embodiment is a sintering method for reducing consumption and reducing CO content in flue gas carried out in a sintering plant in Hebei, comprising the following steps:

[0044] (1) Primary screening of fuel: The fuel is passed through 3 mm, 1 mm and 0.5 mm vibrating screens in sequence to obtain fuel larger than 3 mm, fuel of 1 to 3 mm, fuel of 0.5 to 1 mm and fuel smaller than 0.5 mm, respectively.

[0045] (2) Secondary screening of fuel: the fuel with a particle size larger than 3 mm obtained by screening in step (1) is placed in a crusher for crushing, and then the fuel obtained after crushing is passed through 3 mm, 1 mm and 0.5 mm vibrating screens in sequence, and the fuel with a particle size larger than 3 mm is returned to the crusher for further crushing, and the 1-3 mm fuel obtained by screening is mixed with the 1-3 mm fuel obtained by step (1) to obtain a medium particle size fuel, the 0.5-1 mm fuel obtained by screening is mixed with the 0.5-1 mm fuel obtained by step (1) to obtain a small particle size fuel, and the fuel with a particle size smaller than 0.5 mm obtained by screening is mixed with the fuel with a particle size smaller than 0.5 mm obtained by step (1) to obtain a fine particle size fuel.

[0046] The particle size fuel is ground to less than 200 meshes by a coal mill and then sent to a blast furnace coal injection system as a coal injection raw material.

[0047] The crusher described in this embodiment is a four-roll crusher, and the roller spacing of the upper rollers of the four-roll crusher is 8 mm, and the roller spacing of the lower rollers is 4.5 mm.

[0048] (3) Screening of iron ore: The iron ore is screened through 3 mm and 0.5 mm vibrating screens to obtain large-size ore with a particle size greater than 3 mm, medium-size ore with a particle size of 0.5 to 3 mm, and small-size ore with a particle size less than 0.5 mm.

[0049] (4) Small particle size primary mixing: 45 parts by weight of the medium particle size ore obtained in step (3), 3.5 parts by weight of iron ore concentrate, 2 parts by weight of the small particle size fuel obtained in step (2) and 3.8 parts by weight of flux are placed in a mixer, and 1.5 parts by weight of water is sprayed into the mixer for primary mixing. The mixing time is 3 minutes to obtain a small particle size primary mixture.

[0050] (5) Large particle size single mixing: 45 parts by weight of the large particle size ore obtained in step (3), 5 parts by weight of the small particle size ore obtained in step (3), 2.1 parts by weight of the medium particle size fuel obtained in step (2) and 4.1 parts by weight of the flux are placed in a mixer, and 1.8 parts by weight of water is sprayed into the mixer for single mixing. The mixing time is 3 minutes to obtain a large particle size single mixing.

[0051] (6) Second mixing: the small-size mixed material obtained in step (4) is placed in a granulator for second mixing and granulation, and 2 parts by weight of water is sprayed into the granulator for 1.5 minutes; then the large-size mixed material obtained in step (5) is placed in the granulator, and 1.8 parts by weight of water is sprayed into the granulator for 1.5 minutes to obtain second mixing balls.

[0052] (7) Sintering material distribution: Sintered return ore with a particle size or equivalent particle size greater than 10 mm is spread on the sintering trolley as a base material, and the thickness of the base material is 33 to 50 mm. Then, the two mixed balls obtained in step (6) are spread on the top of the base material by a nine-roller spreading device.

[0053] (8) Hydrogen-rich sintering: Multiple rows of hydrogen nozzles are arranged on the top of the sintering material bed, facing the material bed. The hydrogen nozzles are arranged between the ignition point and the midpoint of the material bed, and the distance from the ignition point to the midpoint of the material bed is divided into three equal parts. The section closest to the ignition point is section A, the middle is section B, and the section closest to the midpoint of the material bed is section C. The number of hydrogen nozzles arranged in section A: the number of hydrogen nozzles arranged in section B: the number of hydrogen nozzles arranged in section C is 3:2:1. While the material bed is moving, the material is continuously distributed in the manner of step (7), and ignition is ignited for sintering at the same time. Hot air is blown downward from the top of the sintering material bed, and negative pressure is set at the bottom of the sintering material bed. The volume concentration of hydrogen injection is 0.72%, and the sintering speed is controlled to be 23.25 mm / min.

[0054] (9) Flue gas circulation: A first smoke exhaust port, a second smoke exhaust port and a third smoke exhaust port are provided on the lower side of the material bed, wherein the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port are arranged in sequence from top to bottom in terms of height. Flue gas discharged from the bottom of the sintering material bed after negative pressure sintering is discharged through the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port, wherein the outlet of the second smoke exhaust port is connected to the externally arranged desulfurization, denitrification treatment and carbon monoxide catalytic adsorption components through a pipeline for discharge, and the first smoke exhaust port and the third smoke exhaust port are connected to the flue gas recycling hood through a pipeline.

[0055] (10) Flue gas recycling: A flue gas recycling hood is arranged on the side of the sealing hood above the sintering material layer. An upper smoke inlet and a lower smoke inlet are arranged at the inlet end of the flue gas recycling hood. The upper smoke inlet is connected to the third smoke exhaust port through a pipe, and the lower smoke inlet is connected to the first smoke exhaust port through a pipe. A plurality of arc-shaped guide plates with their terminals arced downward are arranged at the outlet end of the flue gas recycling hood. The terminals of the arc-shaped guide plates extend beyond the outlet end of the flue gas recycling hood, and the diameter of the outlet end of the flue gas recycling hood is equal to or greater than 100 mm. The effective diameter is greater than the diameter of the inlet end of the smoke recycling hood or an equivalent diameter. The smoke exhausted through the first smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the lower smoke inlet. The smoke exhausted through the third smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the upper smoke inlet. After the recycled smoke is remixed in the smoke recycling hood, it is discharged into the top of the sintering material layer in the sealing hood through the plurality of arc-shaped guide plates, and the recycled smoke re-enters the sintering material layer.

[0056] like Figure 2As shown, the starting end of the arc-shaped guide plate of the flue gas recycling hood is arranged in the flue gas recycling hood, and the terminal end of the arc-shaped guide plate faces the sealing hood and exceeds the outlet end of the oxygen recycling hood; the arc-shaped guide plate of the flue gas recycling hood includes an upper guide plate and a lower guide plate, wherein one or two lower guide plates are arranged, and more than two upper guide plates are arranged, and the distances between the starting ends of adjacent upper guide plates are equal or substantially equal, and the distance between the terminal ends of adjacent upper guide plates is greater than the distance between the starting ends of the two adjacent upper guide plates.

[0057] like Figure 2 As shown, the radius of the arc-shaped upper guide plate decreases from top to bottom, and the radius of the arc-shaped lower guide plate is greater than the radius of the arc-shaped guide plate above the lower guide plate.

[0058] like Figure 2 As shown, in this embodiment, the ratio of the diameter or equivalent diameter D2 of the outlet end of the flue gas recycling hood to the diameter or equivalent diameter D1 of the inlet end of the flue gas recycling hood is 1.4925, which meets the requirement of 1.32≤D2 / D1≤1.65.

[0059] And if Figure 1 As shown, the height h1 of the first smoke exhaust port in this embodiment is less than the height h2 of the second smoke exhaust port, but greater than the height h3 of the third smoke exhaust port, satisfying h2>h1>h3. In this embodiment, h1 is substantially equal to about 90% of h2, and h3 is substantially set to be 30% of h2. Such a setting basically ensures that the ratio of the discharged smoke and the recycled smoke is about 4:6, which can ensure the flow rate of the smoke and stabilize the content of carbon monoxide in the smoke.

[0060] The first smoke exhaust port and the third smoke exhaust port of the present embodiment are also connected to the oxygen-enriched air exhaust port through a pipe. The oxygen-enriched air exhaust port discharges oxygen-enriched air with an oxygen volume content of 23 to 31% into the pipe connected to the first smoke exhaust port and the third smoke exhaust port to balance the lack of oxygen in the flue gas.

[0061] The iron ore materials in this embodiment are foreign ore, mainly Australian ore.

[0062] The fuel of this embodiment is coke powder and anthracite powder, and the weight ratio of coke powder to anthracite powder is 78:22, and the anthracite powder is anthracite powder with an ash content of 8-15wt.% and an ignition temperature of 450-550℃. Such a setting can ensure full combustion and match the main sintering material of 5-5.5mm (a small amount is 4.5-5mm). This embodiment detects the flue gas discharged from the second exhaust port, and the carbon monoxide content is about 3500mg / m 3 (Three tests, the first one was 3502mg / m 3 The second time was 3508 mg / m 3The third time was 3269 mg / m 3 ), which is already lower than the national standard content, and the intensity of subsequent emission treatment is greatly reduced.

[0063] Comparative Example 1

[0064] Based on Example 1, this comparative example does not include steps (1) to (3), and combines steps (4) and (5) into one step. Specifically, 95 parts by weight of ore, 3.5 parts by weight of iron ore concentrate, 4.1 parts by weight of fuel, and 7.9 parts by weight of flux are placed in a mixer, and 3.3 parts by weight of water are sprayed in for a first mixing process. The first mixing process lasts for 6 minutes to obtain a mixture. In step (6), a second mixing process is directly performed instead of adding materials twice. Other settings and raw material ratios are exactly the same as those in Example 1. During the sintering process, the negative pressure required for ventilation is detected to be -16.88 kPa, while the required negative pressure in Example 1 is -13.81 kPa. The carbon monoxide content in the same position as in Example 1 is detected, and the carbon monoxide content in this comparative example is about 4800 mg / m 3 (Three tests, the first one was 4813mg / m 3 The second time was 4838mg / m 3 The third time was 4608 mg / m 3 ), due to the use of hydrogen-rich sintering and flue gas recycling, the carbon monoxide content has been reduced to a certain extent (normally close to 7000mg / m without taking special measures) 3 ), but since there is no specific coordination between the fuel particle size and the ore particle size, it can be seen from the exhaust negative pressure results that the air permeability is much worse than that of Example 1. This is because, firstly, the particle size of the sintered ore is uneven, and the small-size sintered ore fills the gaps between the large-size ore, thereby worsening the air permeability; secondly, the fuel is not mainly distributed in the upper layer, which further worsens the air permeability. The deterioration of the air permeability worsens the complete combustion, so that even through hydrogen enrichment and flue gas recycling, the carbon monoxide content is too high, higher than the national standard, and the subsequent treatment requires a higher intensity.

[0065] Comparative Example 2

[0066] In this comparative example, on the basis of Example 1, in step (6), both materials are directly added to the granulator for secondary mixing, instead of adding materials twice. The other settings and raw material ratios are exactly the same as those in Example 1. After sintering, the negative pressure required for exhaust is detected to be -15.81 kPa, while the negative pressure required for Example 1 is -13.81 kPa. The carbon monoxide content of this comparative example is about 4580 mg / m 3 (Three tests, the first one was 4582mg / m 3The second time was 4591mg / m 3 The third dose was 4565 mg / m 3 ), similarly, due to the use of hydrogen-enriched sintering and flue gas recycling, the carbon monoxide content is reduced to a certain extent, but since there is no secondary mixing of two feedings, although the classification and primary mixing are performed, the mixing time of the two materials is the same, the overall growth, and the obtained particle size is still uneven. The particle size is detected and it is found that the main body is basically evenly distributed between 4 and 6 mm. From the exhaust negative pressure results, it can be seen that the air permeability is better than that of comparative example 1, but much worse than that of embodiment 1. This is due to the uneven particle size of the sintered ore. The small-particle sintered ore fills the gaps between the large-particle ore, thereby deteriorating the air permeability. However, due to the specific distribution of the ore and the fuel, the medium-particle ore is fully combined with the small-particle fuel, so that the fuel is not segregated and distributed in the upper layer, thereby strengthening the top layer heat to a certain extent and improving the air permeability to a certain extent. However, due to the lack of classification and secondary mixing, the air permeability is affected, and the complete combustion is also deteriorated. Even through hydrogen enrichment and flue gas recycling, the carbon monoxide content is too high, higher than the national standard, and the intensity required for subsequent treatment is also high.

[0067] Comparative Example 3

[0068] This comparative example is based on Example 1, but hydrogen-rich sintering is not performed. Other configurations are exactly the same as those of Example 1. After sintering, the results are shown in Table 1.

[0069] Comparative Example 4

[0070] This comparative example is based on Example 1, except that in step (9), three smoke exhaust ports are not provided, but the smoke is directly discharged into two pipes (50 vol. %), one of which is discharged and the other is recycled. The other settings are the same as those in Example 1. The carbon monoxide content in the exhaust pipe is detected and the carbon monoxide content in this comparative example is about 3800 mg / m 3 (Three tests, the first one was 3816mg / m 3 The second time was 3792mg / m 3 The third dose was 3825 mg / m 3 ), the air permeability is basically the same as that of Example 1, but since the flue gas is not classified and reused, the carbon monoxide content in the flue gas is slightly higher than that in Example 1, which proves that Example 1 improves the reuse effect by simply classifying the flue gas according to the position, and mainly reuses the flue gas in the area where the incompletely burned carbon monoxide is concentrated, so as to further reduce the carbon monoxide content in the emission part.

[0071] Comparative Example 5

[0072] This comparative example is based on Example 1, except that no arc-shaped guide plate is provided, and other settings are the same as Example 1. After sintering, the sintered material is tested and it is found that the outer sintered material is overburned, and the measured transfer strength is 73.5 (80.6 measured in Example 1). This is because the recycled flue gas is concentrated toward the outside, while the inside is not in contact with the recycled flue gas, resulting in insufficient surface temperature on the inside, resulting in insufficient sintering on the inside.

[0073] Comparative Example 6

[0074] This comparative example is based on Example 1, except that no arc-shaped guide plate is set, and a straight guide plate is set at the same position and at the same angle. The smoke is tested at the same position as Example 1, and the carbon monoxide content of this comparative example is about 3650 mg / m 3 (Three tests, the first one was 3662mg / m 3 The second time was 3622 mg / m 3 The third dose was 3675 mg / m 3 ), the carbon monoxide content is relatively low, but slightly higher than that of Example 1. It is speculated that the straight guide plate makes the recycled flue gas uneven relative to Example 1, resulting in a slightly worse recycling effect, which proves that the setting method of Example 1 is the most optimized setting method.

Claims

1. A sintering method for reducing consumption and CO content in flue gas, characterized in that: The steps include: (1) Primary screening of fuel: The fuel is passed through 3 mm, 1 mm and 0.5 mm vibrating screens in sequence to obtain fuel larger than 3 mm, fuel 1-3 mm, fuel 0.5-1 mm and fuel smaller than 0.5 mm respectively; (2) Secondary screening of fuel: the fuel with a particle size larger than 3 mm obtained by screening in step (1) is placed in a crusher for crushing, and then the fuel obtained after crushing is sequentially passed through 3 mm, 1 mm and 0.5 mm vibrating screens, and the obtained fuel with a particle size larger than 3 mm is returned to the crusher for further crushing, and the 1-3 mm fuel obtained by screening is mixed with the 1-3 mm fuel obtained by step (1) to obtain a medium particle size fuel, the 0.5-1 mm fuel obtained by screening is mixed with the 0.5-1 mm fuel obtained by step (1) to obtain a small particle size fuel, and the 0.5 mm fuel obtained by screening is mixed with the 0.5 mm fuel obtained by step (1) to obtain a fine particle size fuel; (3) Screening of iron ore: The iron ore is screened through a 3 mm and a 0.5 mm vibrating screen to obtain large-size ore with a particle size greater than 3 mm, medium-size ore with a particle size of 0.5 to 3 mm, and small-size ore with a particle size less than 0.5 mm; (4) small particle size primary mixing: 40 to 50 parts by weight of the medium particle size ore obtained in step (3), 2 to 6 parts by weight of iron ore concentrate, 1.2 to 2.3 parts by weight of the small particle size fuel obtained in step (2), and 3 to 8 parts by weight of flux are placed in a mixer, and 1 to 2 parts by weight of water are sprayed into the mixer for primary mixing. The mixing time is 2 to 4 minutes to obtain a small particle size primary mixture; (5) Large particle size one-mixing: 40-50 weight parts of the large particle size ore obtained in step (3), 2-6 weight parts of the small particle size ore obtained in step (3), 1.3-2.5 weight parts of the medium particle size fuel obtained in step (2) and 3.5-9 weight parts of flux are placed in a mixer, and 1-2 weight parts of water are sprayed into the mixer for one-mixing. The mixing time is 2-4 minutes to obtain a large particle size one-mixing; (6) Second mixing: placing the small-size mixed material obtained in step (4) into a granulator for second mixing and granulation, and spraying 1.5 to 3 parts by weight of water at the same time, and the granulation time is 1 to 2 minutes; then continuing to place the large-size mixed material obtained in step (5) into the granulator, and continuing to spray 1.2 to 2.5 parts by weight of water at the same time, and continuing granulation for 1 to 2 minutes to obtain second-mixed ball; Then sintering is carried out to obtain sintered ore products.

2. The sintering method for reducing consumption and CO content in flue gas according to claim 1, characterized in that: The sintering specifically includes the following steps performed after step (6): (7) Sintering material distribution: sintered return ore with a particle size or equivalent particle size greater than 10 mm is laid on the sintering trolley as a base material, and the thickness of the base material is 33 to 50 mm. Then, the two mixed balls obtained in step (6) are laid on the top of the base material by a nine-roller distribution device in a segregation distribution manner; (8) Hydrogen-rich sintering: multiple rows of hydrogen nozzles are arranged on the top of the sintering material bed, facing the material bed. The hydrogen nozzles are arranged between the ignition point and the midpoint of the material bed, and the distance from the ignition point to the midpoint of the material bed is divided into three equal parts, the section closest to the ignition point is section A, the middle is section B, and the section closest to the midpoint of the material bed is section C, wherein the number of hydrogen nozzles arranged in section A: the number of hydrogen nozzles arranged in section B: the number of hydrogen nozzles arranged in section C is (2.5-3.5): (1.5-2.5): (0.5-1.5), while the material bed is moving, the material is continuously distributed in the manner of step (7), and ignition is ignited for sintering at the same time, hot air is blown downward from the top of the sintering material bed, negative pressure is set at the bottom of the sintering material bed, the volume concentration of hydrogen injection is 0.61-0.98%, and the sintering speed is controlled to be 21.02-26.2 mm / min; (9) Flue gas circulation: A first smoke exhaust port, a second smoke exhaust port and a third smoke exhaust port are provided on the side below the material bed, wherein the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port are arranged in sequence from top to bottom in terms of height position, and the flue gas discharged from the bottom of the sintering material bed after negative pressure sintering is discharged through the first smoke exhaust port, the second smoke exhaust port and the third smoke exhaust port, wherein the outlet of the second smoke exhaust port is connected to the externally arranged desulfurization, denitrification treatment and carbon monoxide catalytic adsorption components through a pipeline for discharge, and the first smoke exhaust port and the third smoke exhaust port are connected to the flue gas recycling hood through a pipeline; (10) Flue gas recycling: A flue gas recycling hood is arranged on the side of the sealing hood above the sintering material layer. An upper smoke inlet and a lower smoke inlet are arranged at the inlet end of the flue gas recycling hood. The upper smoke inlet is connected to the third smoke exhaust port through a pipe, and the lower smoke inlet is connected to the first smoke exhaust port through a pipe. A plurality of arc-shaped guide plates with their terminals arced downward are arranged at the outlet end of the flue gas recycling hood. The terminals of the arc-shaped guide plates extend beyond the outlet end of the flue gas recycling hood, and the diameter of the outlet end of the flue gas recycling hood is equal to or greater than 100 mm. The effective diameter is greater than the diameter of the inlet end of the smoke recycling hood or an equivalent diameter. The smoke exhausted through the first smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the lower smoke inlet. The smoke exhausted through the third smoke exhaust port in step (9) is discharged into the smoke recycling hood through the pipe and the upper smoke inlet. After the recycled smoke is remixed in the smoke recycling hood, it is discharged into the top of the sintering material layer in the sealing hood through the plurality of arc-shaped guide plates, and the recycled smoke re-enters the sintering material layer.

3. The sintering method for reducing consumption and CO content in flue gas according to claim 2, characterized in that: The starting end of the arc guide plate of the flue gas recycling hood is arranged in the flue gas recycling hood, and the terminal end of the arc guide plate faces the sealing hood and exceeds the outlet end of the oxygen recycling hood; the arc guide plate of the flue gas recycling hood includes an upper guide plate and a lower guide plate, wherein one or two lower guide plates are arranged, and more than two upper guide plates are arranged, and the distances between the starting ends of adjacent upper guide plates are equal or substantially equal, and the distance between the terminal ends of adjacent upper guide plates is greater than the distance between the starting ends of the two adjacent upper guide plates.

4. The sintering method for reducing consumption and CO content in flue gas according to claim 3, characterized in that: The radius of the arc-shaped upper guide plate decreases sequentially from top to bottom, and the radius of the arc-shaped lower guide plate is greater than the radius of the arc-shaped guide plate above the lower guide plate.

5. The sintering method for reducing consumption and CO content in flue gas according to claim 2, characterized in that: The diameter or equivalent diameter of the outlet end of the flue gas recycling hood is D2, and the diameter or equivalent diameter of the inlet end of the flue gas recycling hood is D1, satisfying 1.32≤D2 / D1≤1.65; The height of the first smoke exhaust port is h1, the height of the second smoke exhaust port is h2, and the height of the third smoke exhaust port is h3, satisfying h2>h1>h3.

6. The sintering method for reducing consumption and CO content in flue gas according to claim 2, characterized in that: In step (3), the iron ore material is external ore; In step (9), the first smoke exhaust port and the third smoke exhaust port are also connected to the oxygen-enriched air exhaust port through a pipeline, and the oxygen-enriched air exhaust port discharges oxygen-enriched air with an oxygen volume content of 23 to 31% into the pipeline connected to the first smoke exhaust port and the third smoke exhaust port; The flux in step (4) and step (5) is a mixture of 75-85wt.% quicklime and 15-25wt.% dolomite.

7. The sintering method for reducing consumption and CO content in flue gas according to claim 1 or 2, characterized in that: The fuel is coke powder and anthracite powder, and the weight ratio of coke powder to anthracite powder is (70-80): (20-30), and the anthracite powder has an ignition temperature of 450-550°C.

8. The sintering method for reducing consumption and CO content in flue gas according to claim 7, characterized in that: The anthracite powder is anthracite powder with an ash content of 8-15wt.% and an ignition temperature of 450-550°C.

9. The sintering method for reducing consumption and CO content in flue gas according to claim 7, characterized in that: The particle size fuel obtained in step (2) is ground to less than 200 meshes by a coal mill, and then sent to the blast furnace coal injection system as a coal injection raw material.

10. The sintering method for reducing consumption and CO content in flue gas according to claim 1 or 7, characterized in that: The crusher in step (2) is a four-roll crusher, and the roller spacing of the upper roller of the four-roll crusher is 7.5-8.5 mm, and the roller spacing of the lower roller is 3.5-5.5 mm.

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