A sintering method for reducing consumption and reducing the CO content of flue gas

Abstract

The present application relates to a kind of sintering method for reducing consumption and reducing flue gas CO content, including fuel primary screening, fuel secondary screening, iron ore screening, small particle size mixing, large particle size mixing, two mixing and subsequent sintering step, by screening fuel and iron ore, specific particle size fuel and specific particle size iron ore are mixed respectively, then relatively small material is added first, after two mixing for a certain time, then relatively large material is added for continuous two mixing, so that sintering ore particle size is relatively uniform and relatively more fuel can be obtained on the upper layer during sintering, which realizes the effect of reducing consumption and reducing flue gas carbon monoxide content by cooperating with subsequent sintering process setting.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sintered ore sintering, in particular to a sintering method for reducing consumption and CO content of flue gas. BACKGROUND

[0002] Sintered ore is the main raw material for blast furnace ironmaking, so sintering is a very important step in the process of blast furnace ironmaking. Iron ore, iron concentrate, fuel and flux are mixed and granulated under the action of water, and then sintered into blocks on the sintering table through a series of physical and chemical changes. In the existing sintering process, hot air negative pressure sintering is generally used, and hot air is blown from the top of the material layer downward, and negative pressure is set at the bottom of the material layer, so that the hot air fully contacts the material through the pores in the material layer, thereby strengthening the sintering process. In this process, due to the trend of thicker material layer, the importance of material layer permeability gradually emerges. If the permeability is poor, not only the sintering effect will be poor, but also the carbon monoxide content in the flue gas will increase due to incomplete combustion, and the solid consumption will also increase.

[0003] At the same time, with the increasing environmental protection requirements year by year, the research on solid consumption and flue gas control in the sintering process is also gradually valued. In the prior art, a method of using hydrogen-rich injection to replace part of carbonaceous raw materials by hydrogen is adopted. Such a setting not only reduces the solid consumption, but also reduces the carbon-containing gas content in the flue gas. However, the effect of reducing solid consumption and reducing carbon monoxide content in flue gas is limited. If the permeability of the material layer can be further strengthened, and the hot air fully contacts the material in the material layer, then the incomplete combustion will be greatly reduced, thereby further greatly reducing the carbon monoxide content in the flue gas and reducing the solid consumption.

[0004] Chinese patent CN115261615B discloses a sintering batching method for grading and layering of returned ore, which improves the permeability by specific treatment of returned ore, but the improvement effect is limited. SUMMARY

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

[0006] The technical scheme is specifically as follows:

[0007] A sintering method for reducing consumption and CO content of flue gas, comprising the following steps:

[0008] (1) Fuel primary screening: the fuel is sequentially passed through 3mm, 1mm and 0.5mm vibrating screens respectively, to obtain fuel greater than 3mm, fuel of 1-3mm, fuel of 0.5-1mm and fuel less than 0.5mm.

[0009] (2) Fuel secondary screening: the fuel larger than 3 mm obtained from step (1) is put into 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 respectively, the fuel larger than 3 mm obtained is returned to the crusher for further crushing, and the 1-3 mm fuel obtained from screening is mixed with the 1-3 mm fuel obtained from step (1) to obtain medium particle size fuel, the 0.5-1 mm fuel obtained from screening is mixed with the 0.5-1 mm fuel obtained from step (1) to obtain small particle size fuel, and the fuel smaller than 0.5 mm obtained from screening is mixed with the fuel smaller than 0.5 mm obtained from step (1) to obtain micro particle size fuel.

[0010] (3) Iron ore material screening: the iron ore material is passed through 3 mm and 0.5 mm vibrating screens respectively to obtain large particle size ore material larger than 3 mm, medium particle size ore material of 0.5-3 mm and small particle size ore material smaller than 0.5 mm.

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

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

[0013] (6) Second mixing: the small particle size first mixture obtained from step (4) is put into a granulator for second mixing and granulation, 1.5-3 parts by weight of water is sprayed at the same time, the granulation time is 1-2 minutes; then the large particle size first mixture obtained from step (5) is continuously put into the granulator, 1.2-2.5 parts by weight of water is continuously sprayed at the same time, and the granulation is continuously carried out for 1-2 minutes, and the second mixture ball is obtained.

[0014] As preferred, it further comprises:

[0015] (7) Sintering distribution: the sintering return ore with particle size or equivalent particle size larger than 10 mm is laid on a sintering trolley as a bottom layer, the thickness of the bottom layer is 33-50 mm, and then the second mixture ball obtained from step (6) is distributed above the bottom layer by a nine-roller distribution device in a segregation manner.

[0016] (8) Hydrogen-rich sintering: a plurality of hydrogen gas nozzles are arranged on the top of the sintering material layer and face the material layer, the hydrogen gas nozzles are uniformly arranged between the ignition point position and the midpoint position of the material bed, and the distance between the ignition point position and the midpoint position of the material bed is divided into three equal parts, the nearest part to the ignition point is A section, the middle part is B section, and the nearest part to the midpoint of the material bed is C section, wherein the number of hydrogen gas nozzles arranged in the A section: the number of hydrogen gas nozzles arranged in the B section: the number of hydrogen gas nozzles arranged in the C section is (2.5~3.5):(1.5~2.5):(0.5~1.5), the material bed moves while continuously distributing the material in the manner of step (7), and sintering is carried out by ignition at the same time, hot air is blown downward from the top of the sintering material layer, negative pressure is arranged at the bottom of the sintering material layer, the volume concentration of the hydrogen gas blowing is 0.61~0.98%, and the sintering speed is controlled to be 21.02~26.2mm / min.

[0017] (9) Flue gas circulation: a first exhaust port, a second exhaust port and a third exhaust port are arranged on the side of the material bed below, wherein the first exhaust port, the second exhaust port and the third exhaust port are arranged from top to bottom in height position, the flue gas discharged from the bottom of the sintering material layer after negative pressure sintering is discharged through the first exhaust port, the second exhaust port and the third exhaust port, wherein the outlet of the second exhaust port is connected to an externally arranged desulfurization, denitrification treatment and carbon monoxide catalytic adsorption component through a pipeline and then discharged, and the first exhaust port and the third exhaust port are communicated with a flue gas recycling cover through a pipeline.

[0018] (10) Flue gas recycling: the flue gas recycling cover is arranged on the side of the sealing cover at the upper part of the sintering material layer, the inlet end of the flue gas recycling cover is provided with an upper smoke inlet and a lower smoke inlet, wherein the upper smoke inlet is communicated with the third exhaust port through a pipeline, and the lower smoke inlet is communicated with the first exhaust port through a pipeline, a plurality of terminal arc-shaped downward arc-shaped guide plates are arranged at the outlet end of the flue gas recycling cover, the terminal end of the arc-shaped guide plate exceeds the outlet end of the flue gas recycling cover, and the diameter or equivalent diameter of the outlet end of the flue gas recycling cover is greater than the diameter or equivalent diameter of the inlet end of the flue gas recycling cover, the flue gas discharged through the first exhaust port in step (9) is discharged into the flue gas recycling cover through the pipeline and the lower smoke inlet, and the flue gas discharged through the third exhaust port in step (9) is discharged into the flue gas recycling cover through the pipeline and the upper smoke inlet, the recycled flue gas is mixed again in the flue gas recycling cover, and then discharged into the top end of the sintering material layer in the sealing cover through a plurality of arc-shaped guide plates, and the recycled flue gas reenters the sintering material layer.

[0019] As preferred, the start end of the arc-shaped guide plate of the flue gas recycling cover is arranged in the flue gas recycling cover, and the end end of the arc-shaped guide plate is directed to the sealing cover and beyond the outlet end of the oxygen gas recycling cover; the arc-shaped guide plate of the flue gas recycling cover comprises upper layer guide plates and lower layer guide plates, wherein one or two lower layer guide plates are arranged, and more than two upper layer guide plates are arranged, the distance between the start ends of adjacent upper layer guide plates is equal or substantially equal, and the distance between the end ends of adjacent upper layer guide plates is greater than the distance between the start ends of the adjacent two upper layer guide plates.

[0020] As preferred, the radius of the arc-shaped upper layer guide plate decreases from top to bottom in sequence, and the radius of the arc-shaped lower layer guide plate is greater than the radius of the arc-shaped guide plate above the lower layer guide plate.

[0021] As preferred, the diameter or equivalent diameter of the outlet end of the flue gas recycling cover is D2, and the diameter or equivalent diameter of the inlet end of the flue gas recycling cover is D1, and 1.32≤D2 / D1≤1.65 is satisfied.

[0022] As preferred, the height of the first flue gas outlet is h1, the height of the second flue gas outlet is h2, and the height of the third flue gas outlet is h3, and h2>h1>h3 is satisfied.

[0023] As preferred, in step (3), the iron ore material is an external mine (for example, an Australian mine, a South African mine, a Brazilian mine, a Ukrainian mine, a Russian mine, a Kazakhstan mine, and / or an Indian mine, etc.).

[0024] As preferred, the fuel is coke powder and anthracite powder, and the weight ratio of the coke powder to the anthracite powder is (70-80):(20-30), and the anthracite powder is anthracite powder with an ignition temperature of 450-550℃.

[0025] As preferred, the anthracite powder is anthracite powder with an ignition temperature of 450-550℃ and an ash content of 8-15wt.%.

[0026] As preferred, the first flue gas outlet and the third flue gas outlet are also connected to the oxygen-enriched air outlet through a pipeline, and the oxygen-enriched air outlet discharges oxygen-enriched air with an oxygen volume content of 23-31% into the pipeline connected to the first flue gas outlet and the third flue gas outlet.

[0027] As preferred, the particulate fuel obtained in step (2) is ground to 200 mesh or less by a coal mill, and then sent to a blast furnace coal injection system as a coal injection raw material.

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

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

[0030] The technical effect of the present application is that:

[0031] (1) The present application screens the fuel by particle size, screens the iron ore by particle size, mixes the iron ore with different specific particle sizes with the fuel with different specific particle sizes, and adds the mixed material formed by the medium particle size iron ore into the second mixing for a certain period of time, and then adds the mixed material formed by the large particle size iron ore, so that the medium particle size iron ore is formed as the core in the first stage of the second mixing, and then the large particle size nucleation and growth process is continued (i.e. the relatively small particle size iron ore is mixed for a relatively long time), so that the material formed after the second mixing is basically within the range of 5-5.5 mm in particle size, thereby greatly improving the permeability of the material layer during sintering, and avoiding the problem of affecting the permeability caused by the difference in particle size of the material, i.e. the small particle size material fills the gap between the large particle size material. The overall improvement of the permeability 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 the medium particle size ore, iron concentrate and small particle size fuel as the main part of the mixed material for the first time, since the second mixing period of this part of the material is long and the particle size of the iron concentrate is small, relatively more fuel can be adhered to the surface of the medium particle size ore, and the outer layer fuel accounts for a relatively large proportion, so that the density of this part of the material is relatively low compared with the material formed by the relatively large particle size ore. When the nine-roller distribution device is used for distribution, the material with the same particle size and high density is relatively small and falls relatively early, so that the material with medium particle size and more fuel on the surface is distributed in the upper layer during segregation, so that the fuel in the upper layer is more than that in the lower layer, thereby strengthening the development of the surface heat. When the surface heat develops and the fuel is fully burned, the overall permeability of the ore layer is improved, and the gas and the material are in more sufficient contact when the permeability is good, so that the content of CO in the flue gas is controlled.

[0033] (3) The present application sets a specific front-end hydrogen-rich injection to further supplement the development of the surface heat, strengthen the distribution of heat on the upper layer material, and reduce the reaction of carbonaceous raw materials to a certain extent under the condition of the same heat, thereby reducing the content of carbon monoxide in the flue gas from the source, and replacing the carbonaceous raw material with hydrogen to reduce the solid consumption.

[0034] (4) The present application reuses the flue gas by distributing the flue gas and supplementing certain oxygen-rich air, which not only recovers certain energy by bringing the heat of the flue gas back into the sintering material layer, but also fully burns the CO in the flue gas by burning the CO with oxygen in the material layer, thereby greatly reducing the content of carbon monoxide in the flue gas, and reducing the solid consumption by using carbon monoxide and hydrogen as part of the fuel.

[0035] (5) The present application divides the flue gas into three layers, and although the flue gas is not clearly classified, the upper layer is mainly light flue gas (such as carbon monoxide), the lower layer is mainly flue gas carrying a lot of particulate matter, and the middle layer is mainly flue gas containing carbon dioxide. Therefore, by discharging the flue gas in the middle layer (which has been recycled several times), the emission of particulate matter and carbon monoxide is relatively reduced, and the flue gas in the upper and lower layers is reused, which can burn the carbon monoxide in the flue gas and convert it into carbon dioxide, and the particulate matter in the flue gas can further contact the material layer and return to the material layer, thereby reducing the emission of carbon monoxide and particulate matter. Then, by discharging the flue gas in the upper layer into the third flue gas discharge port and discharging the flue gas in the lower layer into the first flue gas discharge port, the relative density of the upper part of the reuse cover is greater than that of the lower part, so that the flue gas can be more fully mixed in the reuse cover due to the relationship between gravity and heat, thereby achieving uniform contact between the flue gas and the material layer when the flue gas is reused.

[0036] (6) Since the existing flue gas reuse cover has a certain flow rate, the flue gas is concentrated on the upper part of the material layer on the side of the reuse cover after being discharged into the material layer, thereby causing the material layer and the reused flue gas to not fully contact. The present application first sets the diameter of the inlet end of the reuse cover to be smaller than the diameter of the outlet end, which reduces the flow rate of the gas to a certain extent, and then sets a guide plate at the outlet end of the flue gas reuse cover, and the outlet end of the guide plate extends beyond the outlet end of the reuse cover, so that the flue gas can flow in the direction of the guide plate. By setting the guide plate to be narrow at the inlet and wide at the outlet, the flow rate of the gas is further reduced, and by setting the upper guide plate to be an arc-shaped structure with the terminal downward and the arc being larger as it goes downward, the flue gas can flow downward at an angle and be further divided after being discharged, thereby achieving the flow of the flue gas in each part. By setting the lower guide plate to have a smaller arc than the upper guide plate, the flue gas is prevented from being concentrated in the upper part of the material layer near the outlet end of the reuse cover, and a certain turbulence is formed in this area, which further promotes the relative uniformity of the flue gas in the upper part of the material layer, thereby enhancing the effect of flue gas reuse. Attached Figure Description

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

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

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

[0040] 201-Sealing hood, 202-Flue gas recovery hood, 221-Upper flue gas inlet, 222-Lower flue gas inlet, 223-Flue gas recovery hood outlet end, 224-Upper guide plate, 225-Lower guide plate, 203-Sintered material layer, D1-Diameter of the inlet end of the flue gas recovery hood, D2-Diameter of the outlet end of the flue gas recovery hood. Detailed Implementation

[0041] The process technology solution of the present invention will be further described below with reference to embodiments and accompanying drawings. Unless otherwise specified, each feature is merely one example of a series of equivalent or similar features. These embodiments are merely for the purpose of aiding understanding the present invention and should not be considered as specific limitations thereof.

[0042] Example 1

[0043] This embodiment describes a sintering method for reducing energy consumption and CO content in flue gas, implemented at a sintering plant in Hebei Province. The method includes the following steps:

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

[0045] (2) Fuel secondary screening: the fuel larger than 3 mm obtained from step (1) is put into 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 respectively, the fuel larger than 3 mm obtained is returned to the crusher for further crushing, and the 1-3 mm fuel obtained from screening is mixed with the 1-3 mm fuel obtained from step (1) to obtain a medium particle size fuel, the 0.5-1 mm fuel obtained from screening is mixed with the 0.5-1 mm fuel obtained from step (1) to obtain a small particle size fuel, and the fuel smaller than 0.5 mm obtained from screening is mixed with the fuel smaller than 0.5 mm obtained from step (1) to obtain a micro particle size fuel.

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

[0047] The crusher is a four-roll crusher, and the roll spacing of the upper roll of the four-roll crusher is 8 mm, and the roll spacing of the lower roll is 4.5 mm.

[0048] (3) Iron ore screening: the iron ore is passed through 3 mm and 0.5 mm vibrating screens respectively to obtain large particle size ore larger than 3 mm, medium particle size ore of 0.5-3 mm and small particle size ore smaller than 0.5 mm.

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

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

[0051] (6) Secondary mixing: the small particle size mixture obtained from step (4) is put into a granulator for secondary mixing and granulation, 2 parts by weight of water is sprayed at the same time, and the granulation time is 1.5 minutes; then the large particle size mixture obtained from step (5) is continuously put into the granulator, 1.8 parts by weight of water is continuously sprayed at the same time, and the granulation is continuously carried out for 1.5 minutes, and a secondary mixed material ball is obtained.

[0052] (7) Sintering distribution: The sintered return fines with particle size or equivalent particle size greater than 10 mm are laid on the sintering trolley as bottom laying material, the thickness of the bottom laying material is 33-50 mm, and then the second mixed material ball segregation distribution obtained in step (6) is distributed on the top of the bottom laying material through the nine-roller distribution device.

[0053] (8) Hydrogen-rich sintering: A plurality of hydrogen gas nozzles are arranged on the top of the sintering material layer and face the material layer, the hydrogen gas nozzles are uniformly arranged between the ignition point position and the material bed midpoint position, and the distance between the ignition point position and the material bed midpoint position is divided into three equal parts, the nearest part to the ignition point is A section, the middle part is B section, and the nearest part to the material bed midpoint is C section, wherein the number of hydrogen gas nozzles arranged in the A section: the number of hydrogen gas nozzles arranged in the B section: the number of hydrogen gas nozzles arranged in the C section is 3:2:1, the material bed moves while continuously distributing in the manner of step (7), and sintering is carried out by ignition at the same time, hot air is blown downward from the top of the sintering material layer, negative pressure is arranged at the bottom of the sintering material layer, the volume concentration of the hydrogen gas blowing is 0.72%, and the sintering speed is controlled to be 23.25 mm / min.

[0054] (9) Flue gas circulation: A first flue gas outlet, a second flue gas outlet and a third flue gas outlet are arranged on the side of the material bed, wherein the first flue gas outlet, the second flue gas outlet and the third flue gas outlet are arranged from top to bottom in height position, the flue gas discharged from the bottom of the sintering material layer after negative pressure sintering is discharged through the first flue gas outlet, the second flue gas outlet and the third flue gas outlet, wherein the outlet of the second flue gas outlet is connected to the outside through a pipeline to arrange a desulfurization, denitrification treatment and carbon monoxide catalytic adsorption component for discharge, and the first flue gas outlet and the third flue gas outlet are communicated with a flue gas recycling cover through a pipeline.

[0055] (10) Flue gas recycling: The flue gas recycling cover is arranged on the side of the sealing cover on the upper part of the sintering material layer, the inlet end of the flue gas recycling cover is provided with an upper flue gas inlet and a lower flue gas inlet, wherein the upper flue gas inlet is communicated with the third flue gas outlet through a pipeline, the lower flue gas inlet is communicated with the first flue gas outlet through a pipeline, a plurality of terminal arc-shaped downward arc-shaped guide plates are arranged at the outlet end of the flue gas recycling cover, the terminal end of the arc-shaped guide plate exceeds the outlet end of the flue gas recycling cover, and the diameter or equivalent diameter of the outlet end of the flue gas recycling cover is greater than the diameter or equivalent diameter of the inlet end of the flue gas recycling cover, the flue gas discharged through the first flue gas outlet in step (9) is discharged into the flue gas recycling cover through the pipeline and the lower flue gas inlet, and the flue gas discharged through the third flue gas outlet in step (9) is discharged into the flue gas recycling cover through the pipeline and the upper flue gas inlet, the recycled flue gas is mixed again in the flue gas recycling cover, and then discharged into the top end of the sintering material layer in the sealing cover through a plurality of arc-shaped guide plates, and the recycled flue gas reenters the sintering material layer.

[0056] As Figure 2As shown, the beginning of the arc-shaped guide plate of the flue gas recycling cover is arranged in the flue gas recycling cover, and the end of the arc-shaped guide plate is directed to the sealing cover and beyond the outlet end of the oxygen recycling cover; the arc-shaped guide plate of the flue gas recycling cover comprises an upper layer guide plate and a lower layer guide plate, wherein the lower layer guide plate is provided with one or two, and the upper layer guide plate is provided with two or more; the distance between the beginnings of adjacent upper layer guide plates is equal or substantially equal, and the distance between the ends of adjacent upper layer guide plates is greater than the distance between the beginnings of the two adjacent upper layer guide plates.

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

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

[0059] And as shown in the drawings, Figure 1 the height h1 of the first flue gas outlet is less than the height h2 of the second flue gas outlet, and greater than the height h3 of the third flue gas outlet, which meets h2>h1>h3. In the embodiment, h1 is substantially equal to about 90% of h2, and h3 is substantially equal to about 30% of h2. Such arrangement basically ensures that the discharged flue gas and the recycled flue gas tend to be in a ratio of about 4:6, which can ensure the flow rate of the flue gas and stabilize the content of carbon monoxide in the flue gas.

[0060] The first flue gas outlet and the third flue gas outlet of the embodiment are also connected to the oxygen-enriched air outlet through a pipeline, and the oxygen-enriched air outlet discharges oxygen-enriched air with an oxygen volume content of 23-31% into the pipeline connected to the first flue gas outlet and the third flue gas outlet, for balancing the lack of oxygen in the flue gas.

[0061] The iron ore material of the embodiment is an imported ore, mainly an Australian ore.

[0062] The fuel of the embodiment is coke powder and anthracite powder, and the weight ratio of the coke powder to the anthracite powder is 78:22, and the anthracite powder has an ash content of 8-15 wt.% and an ignition temperature of 450-550℃. Such arrangement can ensure sufficient combustion and match the main sintering material raw material of 5-5.5 mm (a small amount of 4.5-5 mm). The flue gas discharged from the second flue gas outlet is detected in the embodiment, and the content of carbon monoxide is about 3500 mg / m 3 (three times of detection, the first time is 3502 mg / m 3 , the second time is 3508 mg / m 3The third time was 3269 mg / m³ 3 The concentration at this level is already below the national standard, which greatly reduces the intensity of subsequent emission treatment.

[0063] Comparative Example 1

[0064] Based on Example 1, this comparative example omits 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 concentrate, 4.1 parts by weight of fuel, and 7.9 parts by weight of flux are placed together in a mixer, and 3.3 parts by weight of water are sprayed in for the first mixing. The first mixing time is 6 minutes to obtain the first mixture. In step (6), the second mixing is performed directly instead of adding materials twice. Other settings and raw material ratios are exactly the same as in Example 1. During the sintering process, the required negative pressure 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 this comparative example is detected at the same location as in Example 1 and is approximately 4800 mg / m³. 3 (Three tests were conducted, the first of which showed a concentration of 4813 mg / m³) 3 The second time was 4838 mg / m³ 3 The third time was 4608 mg / m³ 3 Due to the adoption of hydrogen-rich sintering and flue gas recycling methods, the carbon monoxide content has been reduced to a certain extent (normally, without special measures, it is close to 7000 mg / m³). 3 However, due to the lack of specific matching of fuel particle size and ore particle size, the air permeability was significantly worse than in Example 1, as can be seen from the negative pressure results. This is because, firstly, the sintered ore particle size was uneven, with small-diameter sintered ore filling the gaps between large-diameter ore, thus worsening the air permeability; secondly, the fuel was not mainly distributed in the upper layer, further worsening the air permeability. The poor air permeability hindered complete combustion, resulting in excessively high carbon monoxide content, exceeding national standards, even with hydrogen enrichment and flue gas recycling, requiring higher intensity for subsequent treatment.

[0065] Comparative Example 2

[0066] Based on Example 1, this comparative example directly adds both materials to the granulator for secondary mixing in step (6), instead of adding them twice. Other settings and raw material ratios are exactly the same as in Example 1. After sintering, the required negative pressure for ventilation is measured to be -15.81 kPa, while the required negative pressure in Example 1 is -13.81 kPa. Carbon monoxide content at the same location as in Example 1 is measured to be approximately 4580 mg / m³. 3 (Three tests were conducted, the first of which showed a concentration of 4582 mg / m³) 3, the third time was 4565 mg / m 3 , the third time was 4565 mg / m 3 ), and the same due to the use of hydrogen-rich sintering and flue gas recycling, the content of carbon monoxide has a certain decrease, but due to not two times of the second mixing, although the classification of the first mixing, but the mixing time of two kinds of materials is the same, the overall growth, the particle size obtained is still uneven, the particle size is detected, the main body is basically evenly distributed between 4~6mm, from the exhaust negative pressure result can be seen that the permeability is better than that of the comparative example 1, but it is much worse than that of the example 1, which is due to the uneven particle size of the sintered ore, the small particle size of the sintered ore fills the gap between the large particle size of the ore, thereby deteriorating the permeability, but due to the specific allocation of the ore and the fuel, the medium particle size of the ore and the small particle size of the fuel are fully combined, so that the fuel is not segregated and distributed in the upper layer, thereby to a certain extent, the heat of the top layer is strengthened, and the permeability is improved to a certain extent, but due to the lack of classification of the second mixing, the permeability is affected, and the complete combustion is also deteriorated, even through hydrogen enrichment and flue gas recycling, the content of carbon monoxide is too high, higher than the national standard, and the subsequent treatment requires higher intensity.

[0067] Comparative example 3

[0068] The comparative example is based on example 1, the difference is that in step (9), three exhaust ports are not set, but the flue gas is directly discharged into two pipelines (50vol.% each), one of which is discharged, and the other is recycled, and the other settings are the same as example 1. The carbon monoxide content in the position of the exhaust pipeline is detected to obtain the carbon monoxide content of the comparative example, which is about 3800 mg / m 3 (three times, the first time was 3816 mg / m 3 , the second time was 3792 mg / m 3 , the third time was 3825 mg / m 3 ), the permeability is basically the same as example 1, but due to the lack of classification of the flue gas, the content of carbon monoxide in the flue gas is slightly higher than that of example 1, thereby proving that the simple classification and recycling of the flue gas in example 1 improves the recycling effect, and the flue gas in the area where the unburned carbon monoxide is concentrated is recycled, thereby further reducing the content of carbon monoxide in the discharged part.

[0069] Comparative example 4

[0070] The present comparative example is based on example 1, except that no arc-shaped flow guide plate is provided, and other settings are the same as example 1. After sintering, it is found that the outer sintered material is overburned, and the measured strand strength is 73.5 (example 1 is measured as 80.6). This is because the recycled flue gas is concentrated towards the outside, and the inside is not in contact with the recycled flue gas, causing the inside surface layer temperature to be insufficient, thereby causing the inside sintering to be insufficient.

[0071] Comparative example 5

[0072] The present comparative example is based on example 1, except that no arc-shaped flow guide plate is provided, and a straight plate-shaped flow guide plate is provided at the same position and at the same angle. The flue gas is detected at the same position as example 1, and the carbon monoxide content of the present comparative example is about 3650 mg / m 3 (three tests, the first test is 3662 mg / m 3 , the second test is 3622 mg / m 3 , and the third test is 3675 mg / m 3 ). The carbon monoxide content is relatively low, but it is slightly higher than example 1. It is speculated that due to the straight flow guide plate, the recycled flue gas is relatively uneven compared to example 1, resulting in a slight deterioration in recycling effect, thereby proving that the setting method of example 1 is the most optimized setting method.

Claims

1. A sintering method for reducing energy consumption and CO content in flue gas, characterized in that, Includes the following steps: (1) Fuel primary screening: The fuel is passed through vibrating screens of 3mm, 1mm and 0.5mm in sequence to obtain fuel larger than 3mm, fuel of 1~3mm, fuel of 0.5~1mm and fuel smaller than 0.5mm respectively; (2) Secondary screening of fuel: The fuel larger than 3mm obtained by screening in step (1) is placed into the crusher for crushing. Then the fuel obtained after crushing is passed through the vibrating screens of 3mm, 1mm and 0.5mm in sequence. The fuel larger than 3mm is returned to the crusher for further crushing. The fuel of 1~3mm obtained by screening is mixed with the fuel of 1~3mm obtained in step (1) to obtain medium-sized fuel, the fuel of 0.5~1mm obtained by screening is mixed with the fuel of 0.5~1mm obtained in step (1) to obtain small-sized fuel, and the fuel of less than 0.5mm obtained by screening is mixed with the fuel of less than 0.5mm obtained in step (1) to obtain micro-sized fuel. (3) Iron ore screening: The iron ore is screened through vibrating screens of 3 mm and 0.5 mm to obtain large-diameter ore with a particle size greater than 3 mm, medium-diameter ore with a particle size of 0.5~3 mm and small-diameter ore with a particle size less than 0.5 mm. (4) Small particle size mixing: 40-50 parts by weight of medium particle size ore obtained in step (3), 2-6 parts by weight of iron concentrate, 1.2-2.3 parts by weight of small particle size fuel obtained in step (2) and 3-8 parts by weight of flux are placed together in a mixer, and 1-2 parts by weight of water are sprayed in for mixing. The mixing time is 2-4 minutes to obtain small particle size mixing. (5) Large particle size mixing: 40-50 parts by weight of the large particle size ore obtained in step (3), 2-6 parts by weight of the small particle size ore obtained in step (3), 1.3-2.5 parts by weight of the medium particle size fuel obtained in step (2) and 3.5-9 parts by weight of the flux are placed together in a mixer, and 1-2 parts by weight of water are sprayed in for mixing. The mixing time is 2-4 minutes to obtain the large particle size mixing. (6) Second mixing: The small-diameter first mixture obtained in step (4) is placed into the granulator for second mixing and granulation, while 1.5 to 3 parts by weight of water is sprayed in. The granulation time is 1 to 2 minutes. Then, the large-diameter first mixture obtained in step (5) is placed into the granulator, while 1.2 to 2.5 parts by weight of water is sprayed in. The granulation continues for 1 to 2 minutes to obtain the second mixture balls. Then sintering is carried out to obtain sintered mineral products.

2. The sintering method for reducing energy consumption and flue gas CO content according to claim 1, characterized in that, The sintering specifically includes the following steps performed after step (6): (7) Sintering material: 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. The thickness of the base material is 33~50 mm. Then, the two mixed material balls obtained in step (6) are laid on the base material in a segregated manner through a nine-roller material laying device. (8) Hydrogen-rich sintering: Multiple rows of hydrogen nozzles facing the sintering material layer are set on the top of the sintering material layer. The hydrogen nozzles are evenly distributed between the ignition point and the midpoint of the material bed. The distance between the ignition point and 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 in section A: the number of hydrogen nozzles in section B: the number of hydrogen nozzles in section C is (2.5~3.5): (1.5~2.5): (0.5~1.5). While the material bed moves, the material is continuously distributed in the manner of step (7). At the same time, ignition is carried out for sintering. Hot air is blown downward from the top of the sintering material layer. A negative pressure is set at the bottom of the sintering material layer. The volume concentration of hydrogen is 0.61~0.98%, and the sintering speed is controlled at 21.02~26.2 mm / min. (9) Flue gas circulation: A first flue gas outlet, a second flue gas outlet and a third flue gas outlet are provided on the side below the material bed. The first flue gas outlet, the second flue gas outlet and the third flue gas outlet are arranged from top to bottom in terms of height. After negative pressure sintering, the flue gas discharged from the bottom of the sintering material layer is discharged through the first flue gas outlet, the second flue gas outlet and the third flue gas outlet. The outlet of the second flue gas outlet is connected to the external desulfurization, denitrification treatment and carbon monoxide catalytic adsorption components through a pipe for discharge. The first flue gas outlet and the third flue gas outlet are connected to the flue gas recycling hood through a pipe. (10) Flue gas reuse: The flue gas reuse hood is installed on the side of the sealing hood above the sintering material layer. The inlet end of the flue gas reuse hood is provided with an upper flue gas inlet and a lower flue gas inlet. The upper flue gas inlet is connected to the third exhaust port through a pipe, and the lower flue gas inlet is connected to the first exhaust port through a pipe. At the outlet end of the flue gas reuse hood, multiple arc-shaped guide plates with downward arcs at their ends are provided. The ends of the arc-shaped guide plates extend beyond the outlet end of the flue gas reuse hood, and the diameter of the outlet end of the flue gas reuse hood is equal to or greater than that of the sintering material layer. The effective diameter is greater than the diameter of the inlet end of the flue gas recycling hood or the equivalent diameter. In step (9), the flue gas discharged through the first exhaust port is discharged into the flue gas recycling hood through the pipe and the lower exhaust port. In step (9), the flue gas discharged through the third exhaust port is discharged into the flue gas recycling hood through the pipe and the upper exhaust port. After the recycled flue gas is remixed in the flue gas recycling hood, it is discharged into the top of the sintering material layer in the sealing hood through the multiple arc-shaped guide plates. The recycled flue gas re-enters the sintering material layer.

3. The sintering method for reducing energy consumption and flue gas CO content according to claim 2, characterized in that, The starting end of the arc-shaped guide plate of the flue gas reuse hood is located inside the flue gas reuse hood, and the end of the arc-shaped guide plate faces the sealing hood and extends beyond the outlet end of the flue gas reuse hood; the arc-shaped guide plate of the flue gas reuse hood includes an upper guide plate and a lower guide plate, wherein there is one or two lower guide plates and two or more upper guide plates, the distance between the starting ends of adjacent upper guide plates is equal or substantially equal, and the distance between the ends of adjacent upper guide plates is greater than the distance between the starting ends of two adjacent upper guide plates.

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

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

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

7. The sintering method for reducing energy consumption and flue gas CO content 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 is anthracite powder with an ignition temperature of 450~550℃.

8. The sintering method for reducing energy consumption and flue gas CO content according to claim 7, characterized in that, The anthracite pulverized coal has an ash content of 8-15 wt.% and an ignition temperature of 450-550℃.

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

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

Images