A sintering method for reducing the co content of sinter flue gas

Abstract

The present application relates to a kind of sintering method for reducing the CO content of sintering flue gas, by the reasonable cooperation of measures such as layer thickness, material distribution mode, flue gas reuse composite oxygen-enriched sintering and flue gas carbon monoxide catalytic oxidation in each step, the content of carbon monoxide in the emission flue gas is greatly reduced, so that the environmental friendliness of flue gas emission is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of sintering technology for steel sintered ore, and specifically to a sintering method for reducing CO content. Background Technology

[0002] The sintering process of sintered ore is a crucial upstream step in steelmaking, but it also generates a large amount of harmful flue gas. In the entire steelmaking process, the harmful flue gas generated during sintering accounts for nearly 50%, making the treatment of sintered ore flue gas particularly important. Sintered ore flue gas mainly contains nitrogen oxides, sulfur oxides, particulate matter, and carbon monoxide. While research on particulate matter, nitrogen oxides, and sulfur oxides is relatively comprehensive, research on the removal of carbon monoxide has received relatively less attention.

[0003] With increasing environmental awareness and stricter requirements for environmental governance, in addition to strictly limiting the content of harmful substances such as sulfur oxides, nitrogen oxides, and particulate matter, more and more attention is being paid to limiting the content of carbon monoxide in harmful flue gas. Currently, some regions have set carbon monoxide emission standards at 6000 mg / m³. 3 Furthermore, with the gradual increase in environmental emission requirements, it is foreseeable that the lower limit of this standard will be further tightened in the near future.

[0004] The treatment of carbon monoxide in sintering flue gas mainly involves minimizing carbon monoxide generation in the front-end treatment and removing generated carbon monoxide in the back-end treatment. During sintering, carbon monoxide is produced by the incomplete combustion of carbon in the solid fuel: 2C + O2 = 2CO. At the same time, carbon dioxide produced by complete combustion combines with carbon at different locations in the sintering layer to regenerate carbon monoxide: CO2 + C = 2CO. Therefore, reducing carbon monoxide generation during sintering requires not only reasonably promoting complete combustion to reduce the incomplete oxidation of carbon to carbon monoxide, but also controlling and preventing the reaction of carbon dioxide produced by complete combustion with carbon to regenerate carbon monoxide.

[0005] In the back-end treatment process, the catalytic oxidation efficiency of carbon monoxide in flue gas is a key focus for researchers. In existing technologies, the main active components of CO catalytic oxidants are mostly expensive precious metals such as platinum, rhodium, and palladium, and the process is mostly coating. After a period of use, the surface active layer of CO catalytic oxidants prepared by coating will be worn away, and its catalytic activity will be significantly reduced, resulting in catalyst deactivation and decreased efficiency, which increases maintenance costs. A few studies have explored impregnation methods, but existing impregnation processes can result in unevenness, which can significantly reduce the catalytic oxidation effect.

[0006] Chinese invention patent publication CN114733318A discloses a method for treating sintering flue gas. By using a blast furnace to treat the sintering flue gas, it aims to reduce various harmful substances, including carbon monoxide, in the sintering flue gas. However, it only focuses on back-end treatment and does not effectively combine back-end treatment with front-end treatment. Summary of the Invention

[0007] The purpose of this invention is to provide a sintering method for reducing the CO content in sintered ore flue gas, thereby effectively reducing the CO content generated during the sintering process.

[0008] The problem described in this invention is solved by the following technical solution:

[0009] A sintering method for reducing CO content in sintered ore flue gas includes the following steps:

[0010] (1) Raw materials: Prepare 85-95 parts by weight of iron ore powder with TFe of 50-68wt%, 3-6 parts by weight of quicklime, 1-2 parts by weight of dolomite and 5-9 parts by weight of coke powder as sintering raw materials;

[0011] (2) First mixing: Place the sintering raw material prepared in step (1) into the mixer, and then spray in 3-5 parts by weight of water for the first mixing. The mixing time is 5-9 minutes.

[0012] (3) Secondary mixing and granulation: The mixture obtained from the first mixing in step (2) is placed into a secondary high-strength mixer, and 3-5 parts by weight of water is sprayed in at the same time to carry out secondary mixing and granulation to obtain sintered raw material particles. The particle size range of the sintered raw material particles is 0.5-12mm.

[0013] (4) Material bed distribution: A single-layer multi-roller distributor is set above the material bed. The multi-roller distributor is set at an angle, with the direction of material bed movement being the front. The bottom of the multi-roller distributor faces forward, while the top of the multi-roller distributor faces backward. The angle between the multi-roller distributor and the horizontal direction is 33-46°. A circular roller feeder is set above the top of the multi-roller distributor. The direction of rotation of the circular roller feeder is opposite to that of the rollers of the multi-roller distributor. The rotation speed of the circular roller is 5-8 rpm. The rotation speed of each roller in the multi-roller distributor is 10-33 rpm. The moving speed of the material bed is 1.9-2.5 m / min. The sintering raw material particles obtained in step (3) are released to the multi-roller distributor through the circular roller feeder. The sintering raw material particles with larger particle sizes are... The material falls rapidly (with a simultaneous ejection towards the ignition point) to the bottom of the bed. Smaller sintering raw material particles move slowly between the rollers of the multi-roller distributor, eventually settling at the top of the bed. This results in the following structure: 75-96 wt% of sintering raw material particles with a diameter of 5-12 mm in the bottom layer; 65-90 wt% of sintering raw material particles with a diameter of 3-8 mm in the middle layer; and 78-96 wt% of sintering raw material particles with a diameter of less than 5 mm in the top layer. The bottom layer extends from the bottom to one-third of the way up, the top layer extends from the top to one-third of the way down, and the middle layer is the area between the bottom and top layers. The thickness of the distributed material layer is 860-960 mm.

[0014] (5) Flue gas reuse and oxygen-enriched sintering; a fume hood is set above the material bed, and a mixed flue gas discharge pipe is set on the top of the fume hood. Multiple air boxes are set below the material bed. By drawing negative pressure, the gas flows from the top of the material bed down through the material bed and is discharged from the bottom of the air boxes. While the material bed moves, the material is continuously distributed in the manner of step (4), and ignition is carried out to start sintering. A mixing chamber is connected to the ignition furnace. The volume content of industrial pure oxygen in the mixing chamber is set to 23-28%. Ignition is carried out using oxygen-enriched gas in the mixing chamber. The ignition temperature is 1165-111°C. At 80℃, the blowers are started simultaneously to create negative pressure below the material layer through multiple air boxes. The flue gas discharged from the bottom of the air boxes is connected to the flue gas treatment pipeline and the flue gas recycling pipeline. The outlet end of the flue gas recycling pipeline is connected to the inlet end of the mixed flue gas discharge pipeline, and the inlet end of the mixed flue gas discharge pipeline is simultaneously connected to the oxygen discharge pipeline. The oxygen and flue gas are mixed in the mixed flue gas discharge pipeline and then discharged to the surface of the material layer through the fume hood. The oxygen volume content in the mixed flue gas discharge pipeline is set to 25-28%. Flue gas recycling and oxygen-enriched sintering are carried out to obtain sintered ore products.

[0015] (6) Flue gas treatment: An electrostatic precipitator, an activated carbon desulfurization unit, a carbon monoxide catalytic oxidation device, an SCR denitrification unit, and a circulating fan are sequentially installed on the flue gas treatment pipeline. The carbon monoxide catalytic oxidation device includes an induced draft pipe, an inlet bend, a catalytic oxidation kiln, a catalytic oxidation block, an outlet bend, and a return air pipe. Both the induced draft pipe and the return air pipe are closed pipes with both ends closed. The induced draft pipe and the return air pipe are arranged parallel or approximately parallel. Both the induced draft pipe and the return air pipe are not parallel to the flue gas treatment pipeline. An inlet and an outlet are provided on the side wall of the induced draft pipe. The inlet is connected to the flue gas... The front end of the treatment pipeline is connected, the exhaust port of the induced draft pipe is connected to the inlet end of the inlet bend, the outlet end of the inlet bend is connected to the top opening of the catalytic oxidation kiln, multiple catalytic oxidation blocks are arranged inside the catalytic oxidation kiln, the bottom opening of the catalytic oxidation kiln is connected to the inlet end of the outlet bend, a catalytic gas inlet and a catalytic gas outlet are provided on the side wall of the return air pipe, the outlet end of the outlet bend is connected to the catalytic gas inlet of the return air pipe, and the catalytic gas outlet is connected to the front end of the rear section of the flue gas treatment pipeline; the end of the flue gas treatment pipeline is connected to the exhaust chimney, through which the treated flue gas is discharged.

[0016] In the above-mentioned sintering method for reducing CO content in sintered ore flue gas, the multiple wind boxes in step (5) are divided into five wind box groups from front to back, with the direction closest to the ignition point being the front. The number of wind boxes in the first wind box group is 10-15% of the total number of wind boxes, the number of wind boxes in the second wind box group is 20-25%, the number of wind boxes in the third wind box group is 35-40%, the number of wind boxes in the fourth wind box group is 20-25%, and the number of wind boxes in the fifth wind box group is 5-9%. The flue gas discharged from the bottom of the wind boxes in the first, third, and fifth wind box groups is connected to the flue gas treatment pipeline, and the flue gas discharged from the bottom of the wind boxes in the second and fourth wind box groups is connected to the flue gas reuse pipeline. The volume ratio of the flue gas entering the flue gas treatment pipeline to the flue gas reuse pipeline is (65-75):(25-35).

[0017] In the above-mentioned sintering method for reducing CO content in sintered ore flue gas, in step (5), an electrostatic precipitator and a circulating fan are sequentially installed on the flue gas recycling pipeline.

[0018] In the above sintering method for reducing CO content in sintered ore flue gas, in step (5), the oxygen content in the gas discharged into the material layer is 17-22%.

[0019] The above-mentioned sintering method for reducing CO content in sintered ore flue gas includes a separate oxygen-enriched air pipe installed at the rear of the material layer in the fume hood, which sprays oxygen-enriched air toward the material layer. The oxygen content of the oxygen-enriched air is 29-38%.

[0020] In the above-mentioned sintering method for reducing CO content in sintered ore flue gas, the catalytic oxidation block in step (6) is a composite rectangular block with zirconium mullite honeycomb ceramic as the carrier and an aqueous solution of copper nitrate and cerium nitrate as the active catalytic component. Each zirconium mullite honeycomb ceramic block is provided with multiple vertically arranged through holes with a diameter of 1.5-2.5 mm and a wall thickness of 0.8-1.3 mm between the through holes. The zirconium content of the zirconium mullite honeycomb ceramic is 0.9-1.8 wt%.

[0021] The above-mentioned sintering method for reducing CO content in sintered ore flue gas includes the following steps in step (6): I. Calcination of zirconium-containing mullite honeycomb ceramics; II. Preparation of a composite aqueous solution of copper nitrate and cerium nitrate; III. Placement of the zirconium-containing mullite honeycomb ceramics obtained in step I into the aqueous solution prepared in step II, setting a stirring paddle to form a vortex in the aqueous solution, setting the direction of the densely distributed through holes of the zirconium-containing mullite honeycomb ceramics to face the direction of the vortex flow, and impregnation for 10-15 hours; IV. Calcination of the catalytic oxidation block obtained in step III.

[0022] The above-mentioned sintering method for reducing CO content in sintered ore flue gas, the preparation method of the catalytic oxidation block in step (6) includes the following steps: I, after cleaning, the zircon-containing mullite honeycomb ceramic is placed in a calcining furnace for calcination at a calcination temperature of 380-620℃ for 0.8-2.2 hours; II, Cu is weighed according to the weight ratio of (1-6):(0.8-1.2). (NO3)2·6H2O and Ce(NO3)3·6H2O are mixed with deionized water to prepare a compound aqueous solution with a concentration of 0.38-2 mol / L; III. The zircon-containing mullite honeycomb ceramic obtained in step I is placed into the aqueous solution prepared in step II. A stirring paddle is set on the surface of the aqueous solution to form a vortex. The densely packed through holes of the zircon-containing mullite honeycomb ceramic are oriented in the direction of the vortex flow. After immersion for 10-15 hours, the catalytic oxidation block is taken out to obtain the immersion block; IV. The catalytic oxidation block obtained in step III is placed in a calcining furnace and heated to 180-280℃ in an inert gas protective atmosphere. After holding at the temperature for 3.5-5 hours, it is cooled to obtain the catalytic oxidation block product.

[0023] In the above-mentioned sintering method for reducing CO content in sintered ore flue gas, the catalytic oxidation blocks are arranged in multiple layers in the catalytic oxidation kiln, and the length and width of each layer of catalytic oxidation blocks are not equal, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane, or the catalytic oxidation blocks in each layer are staggered, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane; the densely distributed through holes of all the catalytic oxidation blocks are respectively open to the bottom and top of the catalytic oxidation kiln.

[0024] Preferably, a support frame is provided on the material bed, the height of which is such that the top of the support frame is located at the bottom of the sintered ore layer and the top of the combustion softening layer of the material bed.

[0025] During the sintering process, the material layer is divided into the following layers from top to bottom: sintered ore layer (or sintered ore zone) (above 1200℃), combustion softening layer (or combustion zone) (700-1200℃), preheating layer (or drying preheating zone) (100-700℃), over-wet layer (or over-wet zone) (70-100℃), and raw material layer (around 60℃ or below).

[0026] Preferably, a hydrogen nozzle is vertically installed through the fume hood. The hydrogen nozzle is located above the front of the material bed and behind the ignition point. The volume concentration of hydrogen is 0.52-0.91%, the sintering speed is controlled at 20.82-25.2 mm / min, the ignition point is point A, the midpoint of the material bed is point B, and the midpoint between points A and B is point C. The number of hydrogen nozzles between points A and C is 2-5 times the number between points B and C.

[0027] The technical advantages of this invention are as follows:

[0028] (1) This invention achieves a gradual decrease in particle size from bottom to top by rationally setting the multi-roller feeder to the proportion of particle size in each layer of the feed material. Furthermore, by using a single-layer multi-roller feeder, it realizes a feeding method with larger particles at the bottom and smaller particles at the top. Compared to multi-layer feeders, this further reduces excessive collisions between the particles obtained from the secondary mixing granulation process and the feeder, thus reducing the amount of powder produced. Combined with thick feed layers, flue gas recycling, and oxygen enrichment measures, the permeability of the feed layer is enhanced, and the coordination with these measures is strengthened, thereby improving complete combustion and significantly reducing CO production.

[0029] (2) By setting up a thick material layer in the overall material layer structure based on the specific material distribution method, the thick material layer enhances the heat storage effect and improves the utilization of waste heat in the upper sintering layer, thereby reducing solid fuel consumption and heat consumption, and thus reducing the proportion of CO generated in the flue gas. However, if the thick material layer is set alone, the permeability will be reduced. This invention, combined with the specific material distribution method of large at the bottom and small at the top and enhanced oxygen enrichment, avoids adverse consequences such as reduced oxygen potential. Based on the thick material layer, its advantages are enhanced while its disadvantages are reduced by combining other measures, thereby enhancing complete combustion and reducing CO generation as a whole.

[0030] (3) By adopting flue gas recycling (further combustion of CO in flue gas) and oxygen enrichment, the secondary combustion of carbon monoxide in flue gas is further enhanced. Since the sintering flue gas circulation will result in low O2 content, affecting the quality of sintered ore and increasing CO generation, the oxygen enrichment operation increases the oxygen potential, which can reduce solid fuel consumption and achieve CO emission reduction. At the same time, the sintered ore production and quality are improved, and the solid consumption per ton of ore and CO emission are further reduced, so that the combustion process of flue gas mixed with air in the material layer is more complete. By reasonably setting the ratio of exhaust flue gas and recycled flue gas and the location of recycled flue gas (by reasonably selecting the location of the wind box, the location with higher CO content is reasonably selected for recycling), the flue gas is recycled in the most optimized way. Since a material layer with better air permeability is set, the gas flow in the material layer is smoother, and the effect of oxygen enrichment and flue gas recycling is more obvious. This means that the specific material distribution method of flue gas recycling, oxygen-enriched sintering, and thick material layer is coordinated with each other, thereby reducing CO generation from the source and process, and thus significantly reducing the CO content in the flue gas.

[0031] (4) By setting up support frames at specific locations, the load on the lower material layer is reduced and the permeability of the lower material layer is improved, thereby increasing the oxygen potential in the material layer and increasing the degree of combustion, thus reducing the amount of CO produced by combustion, which can serve as an effective supplement to the aforementioned measures.

[0032] (5) By specifically defining the impregnation method and placement method of the catalytic oxidation block, the impregnation is more thorough and uniform by coordinating the contact method between the liquid and the zircon-containing mullite honeycomb ceramic during the impregnation process; by setting the structure of each component of the specific carbon monoxide catalytic oxidation device, and in conjunction with the specific placement method of the catalytic oxidation block, the flue gas flows through the porous structure as much as possible during the downward flow process from the top, and this setting increases the residence time of the flue gas in the catalytic oxidation kiln, thereby strengthening the adsorption intensity of CO in the flue gas and reducing the amount of CO emitted in the subsequent flue gas. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the sintering gas flow in one embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the carbon monoxide catalytic oxidation device of the present invention.

[0035] Wherein: 100-material layer, 101-fume hood, 102-mixed flue gas discharge pipe, 103-oxygen, 104-flue gas reuse pipe, 105-wind box, 106-flue gas treatment pipe, 107-electrostatic precipitator on flue gas reuse pipe, 108-first circulating fan, 109-electrostatic precipitator on flue gas treatment pipe, 110-second circulating fan, 111-chimney, 112-activated carbon desulfurization component, carbon monoxide catalytic oxidation device and SCR denitrification component, 201-flue gas inlet, 202-induced draft pipe, 203-inlet bend, 204-catalytic oxidation kiln, 205-outlet bend, 206-return air pipe, 207-catalytic gas outlet, 208-catalytic oxidation block. Detailed Implementation

[0036] The technical solution of the present invention will be further described in conjunction with the embodiments: Example 1

[0037] A sintering method for reducing CO content in sintered ore flue gas, implemented at a steel plant in Hebei Province, is as follows: Figure 1 and Figure 2 As shown, it includes the following steps:

[0038] (1) Ingredients: 90 parts by weight of iron ore powder with 65 wt% TFe, 5 parts by weight of quicklime, 1.5 parts by weight of dolomite and 8 parts by weight of coke powder are prepared as sintering raw materials.

[0039] (2) First mixing: The sintering raw material prepared in step (1) is placed into the mixer, and then 3.5 parts by weight of water is sprayed in for the first mixing. The mixing time is 8 minutes.

[0040] (3) Secondary mixing and granulation: The mixture obtained from the first mixing in step (2) is placed into a secondary high-strength mixer, and 4.5 parts by weight of water is sprayed in at the same time to carry out secondary mixing and granulation to obtain sintered raw material particles. The particle size range of the sintered raw material particles is 0.5-12mm.

[0041] (4) Material distribution on the material bed: A single-layer multi-roller distributor is installed above the material bed. The multi-roller distributor is inclined, with the direction of material bed movement being the front, and the bottom end of the multi-roller distributor facing forward (i.e., as shown in the image). Figure 1 Facing to the right), while the top of the multi-roller feeder faces backward, and the angle between the multi-roller feeder and the horizontal direction is 39°. A circular roller feeder is installed above the top of the multi-roller feeder, and the rotation direction of the circular rollers of the circular roller feeder is opposite to the rotation direction of the individual rollers of the multi-roller feeder (e.g., facing to the right). Figure 1In this implementation, the circular rollers of the circular roller feeder rotate clockwise, while the rollers of the multi-roller distributor rotate counterclockwise. The rotation speed of the circular rollers is 6 rpm, the rotation speed of each roller in the multi-roller distributor is 18 rpm, the roller gap of the distribution rollers is 2-8 mm (5.5 mm in this embodiment), and the moving speed of the material bed is 2.2 m / min. The sintering raw material particles obtained in step (3) are released to the multi-roller distributor through the circular roller feeder. The larger sintering raw material particles are first laid to the bottom of the material bed, while the smaller sintering raw material particles are slowly laid between the rollers of the multi-roller distributor. The material moves between layers, and the main body is eventually placed at the top of the material layer, so that the proportion of sintered raw material particles with a diameter of 5-12mm in the bottom layer is 92wt%, the proportion of sintered raw material particles with a diameter of 3-8mm in the middle layer is 88wt%, and the proportion of sintered raw material particles with a diameter of less than 5mm in the top layer is 90wt%. The bottom layer is from the bottom of the material layer to 1 / 3 of the height above, the top layer is from the top of the material layer to 1 / 3 of the height below, and the middle layer is the part between the bottom layer and the top layer. The thickness of the material layer is 890mm (thick material layer).

[0042] like Figure 1 As shown, (5) flue gas is recycled and oxygen-enriched for sintering; a fume hood is set above the material bed, and a mixed flue gas discharge pipe is set on the top of the fume hood. Multiple air boxes are set below the material layer. By drawing negative pressure, the gas flows from the top of the material layer down through the material layer and is discharged from the bottom of the air box. While the material bed moves, the material is continuously distributed in the manner of step (4), and ignition is carried out to start sintering. A mixing chamber is connected to the ignition furnace. The volume content of industrial pure oxygen in the mixing chamber is set to 26%. Ignition is carried out using oxygen-enriched gas in the mixing chamber. The ignition temperature is 1165-11 At 80℃, the blowers are started simultaneously to create negative pressure below the material layer through multiple air boxes. The flue gas discharged from the bottom of the air boxes is connected to the flue gas treatment pipeline and the flue gas recycling pipeline. The outlet end of the flue gas recycling pipeline is connected to the inlet end of the mixed flue gas discharge pipeline. The inlet end of the mixed flue gas discharge pipeline is also connected to the oxygen discharge pipeline. The oxygen and flue gas are mixed in the mixed flue gas discharge pipeline and then discharged to the surface of the material layer through the fume hood. The oxygen volume content in the mixed flue gas discharge pipeline is set to 25-28%. Flue gas recycling and oxygen-enriched sintering are carried out to obtain sintered ore products.

[0043] like Figure 1As shown, this embodiment has five bellows groups, totaling 18 bellows. The direction closest to the ignition point is the front. The first bellows group consists of bellows 1 and 2, the second bellows group consists of bellows 3-6, the third bellows group consists of bellows 7-13, the fourth bellows group consists of bellows 14-17, and the fifth bellows group consists of bellows 18. The flue gas discharged from the bottom of the bellows in the first, third, and fifth bellows groups is connected to the flue gas treatment pipeline, while the flue gas discharged from the bottom of the bellows in the second and fourth bellows groups is connected to the flue gas recycling pipeline. The volume ratio of the flue gas entering the flue gas treatment pipeline to the flue gas recycling pipeline is 70:30.

[0044] (6) Flue gas treatment: An electrostatic precipitator, an activated carbon desulfurization unit, a carbon monoxide catalytic oxidation device, an SCR denitrification unit, and a circulating fan are sequentially installed on the flue gas treatment pipeline. The carbon monoxide catalytic oxidation device includes an induced draft pipe, an inlet bend, a catalytic oxidation kiln, a catalytic oxidation block, an outlet bend, and a return air pipe. Both the induced draft pipe and the return air pipe are closed pipes with both ends closed. The induced draft pipe and the return air pipe are arranged parallel or approximately parallel. Both the induced draft pipe and the return air pipe are not parallel to the flue gas treatment pipeline. An inlet and an outlet are provided on the side wall of the induced draft pipe. The inlet is connected to the flue gas... The front end of the treatment pipeline is connected, the exhaust port of the induced draft pipe is connected to the inlet end of the inlet bend, the outlet end of the inlet bend is connected to the top opening of the catalytic oxidation kiln, multiple catalytic oxidation blocks are arranged inside the catalytic oxidation kiln, the bottom opening of the catalytic oxidation kiln is connected to the inlet end of the outlet bend, a catalytic gas inlet and a catalytic gas outlet are provided on the side wall of the return air pipe, the outlet end of the outlet bend is connected to the catalytic gas inlet of the return air pipe, and the catalytic gas outlet is connected to the front end of the rear section of the flue gas treatment pipeline; the end of the flue gas treatment pipeline is connected to the exhaust chimney, through which the treated flue gas is discharged.

[0045] In this embodiment, the catalytic oxidation block is a composite rectangular block with zirconium-containing mullite honeycomb ceramic as the carrier and an aqueous solution of copper nitrate and cerium nitrate as the active catalytic component. Each zirconium-containing mullite honeycomb ceramic block is provided with multiple vertically arranged dense through holes with a pore diameter of 2.1 mm and a wall thickness of 1.1 mm between the through holes. The zirconium content of the zirconium-containing mullite honeycomb ceramic is 1.6 wt%.

[0046] The preparation method of the catalytic oxidation block in this embodiment includes the following steps: I. After cleaning, the zirconium-containing mullite honeycomb ceramic is placed in a calcination furnace for calcination at a temperature of 560°C for 1.6 hours; II. Cu(NO3)2·6H2O and Ce(NO3)3·6H2O are weighed in a weight ratio of 5:1.1 and then mixed with deionized water to prepare a compound aqueous solution with a concentration of 1.2 mol / L; III. The zirconium-containing mullite honeycomb ceramic obtained in step I is placed into the aqueous solution prepared in step II. A stirring paddle is set on the surface of the aqueous solution to form a vortex. The densely packed through holes of the zirconium-containing mullite honeycomb ceramic are oriented towards the direction of the vortex flow. After immersion for 13 hours, the catalytic oxidation block is removed to obtain the immersion block; IV. The catalytic oxidation block obtained in step III is placed in a calcination furnace and heated to 260°C in an inert gas atmosphere. After holding at that temperature for 3.9 hours, it is cooled to obtain the catalytic oxidation block product.

[0047] like Figure 1 As shown, an electrostatic precipitator is also installed on the flue gas recycling pipeline.

[0048] like Figure 1 As shown, a first circulating fan is installed on the flue gas reuse pipeline, and a second circulating fan is installed on the flue gas treatment pipeline.

[0049] In this embodiment, the oxygen content in the gas discharged into the material layer is 18% (the oxygen content inside the material layer).

[0050] In other embodiments, an oxygen-enriched air duct can be separately provided at the rear of the material layer in the fume hood to spray oxygen-enriched air toward the material layer. The oxygen content of the oxygen-enriched air is 29-38%, thereby supplementing the oxygen content at the rear.

[0051] like Figure 2 As shown, the catalytic oxidation blocks are arranged in multiple layers in the catalytic oxidation kiln, and the length and width of each layer of catalytic oxidation blocks are not equal, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane, or the catalytic oxidation blocks in each layer are staggered, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane; the densely packed through holes of all the catalytic oxidation blocks are respectively open to the bottom and top of the catalytic oxidation kiln.

[0052] In other embodiments, a support frame can be provided on the material bed, the height of which is such that the top of the support frame is located at the bottom of the sintered ore layer and the top of the combustion softening layer. In conventional sintering, the material bed is divided from top to bottom into a sintered ore layer (or sintered ore zone) (above 1200℃), a combustion softening layer (or combustion zone) (700-1200℃), a preheating layer (or drying preheating zone) (100-700℃), a super-wet layer (or super-wet zone) (70-100℃), and a raw material layer (around 60℃ or below). Placing the support frame at the bottom of the sintered ore layer provides support, ensuring the permeability of the material below, thereby further enhancing the effect of complete combustion and reducing CO production.

[0053] In other embodiments, hydrogen nozzles can be vertically installed through the fume hood. The hydrogen nozzles are located above the front of the material bed and behind the ignition point. The volume concentration of hydrogen injected is 0.81%, the sintering speed is controlled at 22.1 mm / min, the ignition point is point A, the midpoint of the material bed is point B, and the midpoint between points A and B is point C. The number of hydrogen nozzles between points A and C is 2-5 times the number between points B and C (that is, as many hydrogen nozzles as possible are placed at the front end of the front section, so that hydrogen is added as fuel at the front position, which reduces the combustion of C to a certain extent, thereby reducing the production of CO while providing heat at the front).

[0054] Testing revealed that the carbon monoxide content in the flue gas emitted in this embodiment was approximately 3600 mg / m³. 3 (Three tests were conducted, the first of which showed a concentration of 3602 mg / m³) 3 The second time was 3608 mg / m³ 3 The third time was 3598 mg / m³ 3 ). Comparative Example 1

[0055] Similarly, a comparative example was set up at a steel plant in Hebei Province, based on Example 1. This comparative example used a conventional feeder for material distribution. The results showed that the proportion of sintered raw material particles with a diameter of 5-12 mm in the bottom layer was 66 wt%, while the proportion of sintered raw material particles with a diameter smaller than 5 mm in the top layer was 72 wt%. Although the proportion of smaller particles was higher in the upper layer than in the lower layer, this is due to the conventional falling of different particles during conventional feeding. Furthermore, the carbon monoxide catalytic oxidation device in this comparative example used a known conventional catalyst and did not have an exhaust duct, inlet bend, outlet bend, or return air duct. Other setup methods were the same as in Example 1. After the same sintering treatment as in Example 1, the carbon monoxide content in the exhaust gas was measured to be approximately 7200 mg / m³. 3(Three tests were conducted, the first of which showed a result of 7189 mg / m³) 3 The second time was 7210 mg / m³ 3 The third time was 7202 mg / m³ 3 This is because the fabric was not laid out in a way that was smaller at the top and larger at the bottom, which meant that the permeability and gas flow were not optimized during the sintering process. As a result, although flue gas recycling and oxygen enrichment were used, their utilization was not optimized, leading to wasted oxygen. At the same time, the catalytic oxidation of carbon monoxide in the flue gas was not complete, resulting in a relatively high carbon monoxide content. Comparative Example 2

[0056] Similarly, at a steel plant in Hebei Province, this comparative example was set up in accordance with Example 1. The material layer thickness of this comparative example was 810 mm, and other settings were the same as in Example 1. The carbon monoxide content in the emitted flue gas was detected, and the carbon monoxide content of this comparative example was approximately 4200 mg / m³. 3 (Three tests were conducted, the first of which showed a result of 4201 mg / m³) 3 The second time was 4210 mg / m³ 3 The third time was 4202 mg / m³ 3 It is generally believed that sintering a thicker material layer, increasing the thickness by 80 mm, will reduce the CO concentration by 500 mg / m³. 3 However, compared to the control group, the material layer thickness decreased by 80 mm, and the CO concentration increased by 600 mg / m³. 3 In other words, the thick material layer does not independently affect the amount of CO generated, but can further optimize the effect when combined with other measures. The comparative example shows that reducing the material layer thickness alone increased the CO concentration even more, indicating that the optimization effect of the material layer thickness in combination with the particle size of each layer of material, as well as the combination of flue gas recycling and oxygen content, is more optimized by the combination method of the present invention. Comparative Example 3

[0057] Similarly, at a steel plant in Hebei Province, a comparative example was set up based on Example 1. This comparative example did not use oxygen-enriched ignition; conventional ignition was employed. Other settings were the same as in Example 1. The ignition temperature was found to be approximately 200°C lower, the spin strength was measured to be 72.7 (79.6 in Example 1), the yield was 80.2% (86.5% in Example 1), and the CO content in the flue gas increased slightly by less than 80 mg / m³. 3 This is because using conventional ignition (instead of oxygen-enriched ignition) lowers the preheating temperature, increases the amount of returned ore, and deteriorates the quality of the surface sinter, thus weakening the CO emission reduction effect. Comparative Example 4

[0058] Similarly, a comparative example was set up at a steel plant in Hebei Province, based on Example 1. This comparative example did not use oxygen enrichment, meaning no oxygen was introduced into the mixed flue gas discharge pipe. Other setup methods were the same as in Example 1. The carbon monoxide content in the emitted flue gas was measured to be approximately 5320 mg / m³. 3 (Three tests were conducted, the first of which showed a concentration of 5328 mg / m³) 3 The second time was 5318 mg / m³. 3 The third time was 5326 mg / m³. 3 Although flue gas recycling was used, no oxygen enrichment process was performed on the recycled flue gas. Because the flue gas replaced part of the original air, the volume fraction of oxygen in the material layer was far below 18%, which greatly increased the proportion of incomplete combustion during the sintering process. Although catalytic oxidation of carbon monoxide in the flue gas was used, the excessive amount of carbon monoxide in the original flue gas resulted in a significant increase in the carbon monoxide content in the final flue gas compared to the example. Comparative Example 5

[0059] Similarly, in a steel plant in Hebei Province, a comparative example was set up based on Example 1. In this comparative example, the catalytic oxidation block was equipped with a stirring paddle during the impregnation step, but instead of aligning the densely packed through-holes of the zirconium-containing mullite honeycomb ceramic with the direction of the vortex flow, it was placed randomly. Other setup methods were the same as in Example 1. It was observed that the active components impregnated with the zirconium-containing mullite honeycomb ceramic were relatively uneven compared to Example 1. The carbon monoxide content in the emitted flue gas was measured to be approximately 3730 mg / m³ in this comparative example. 3 (Three tests were conducted, the first of which showed a concentration of 3658 mg / m³) 3 The second time was 3751 mg / m³. 3 The third time was 3735 mg / m³. 3 The three tests showed significant differences, indicating that the catalytic oxidation effect of carbon monoxide varied at different times and along its flow path, resulting in unstable carbon monoxide treatment and an overall decline in effectiveness. Comparative Example 6

[0060] Similarly, in a steel plant in Hebei Province, a comparative example was set up based on Example 1. The catalytic oxidation blocks in this comparative example were arranged neatly, with interconnected gaps between each layer; other arrangements were the same as in Example 1. The carbon monoxide content in the emitted flue gas was measured to be approximately 3680 mg / m³. 3 (Three tests were conducted, the first of which showed a concentration of 3696 mg / m³) 3 The second time was 3701 mg / m³ 3 The third time was 3678 mg / m³ 3 This configuration reduces the contact time between the gas and the catalytic oxidation block, thereby weakening the catalytic oxidation effect.

Claims

1. A sintering method for reducing CO content in sintered ore flue gas, characterized in that, Includes the following steps: (1) Raw materials: Prepare 85-95 parts by weight of iron ore powder with TFe of 50-68wt%, 3-6 parts by weight of quicklime, 1-2 parts by weight of dolomite and 5-9 parts by weight of coke powder as sintering raw materials; (2) First mixing: Place the sintering raw material prepared in step (1) into the mixer, and then spray in 3-5 parts by weight of water for the first mixing. The mixing time is 5-9 minutes. (3) Secondary mixing and granulation: The mixture obtained from the first mixing in step (2) is placed into a secondary high-strength mixer, and 3-5 parts by weight of water is sprayed in at the same time to carry out secondary mixing and granulation to obtain sintered raw material particles. The particle size range of the sintered raw material particles is 0.5-12mm. (4) Material bed distribution: A single-layer multi-roller distributor is set above the material bed. The multi-roller distributor is set at an angle, with the direction of material bed movement being the front. The bottom of the multi-roller distributor faces forward, while the top of the multi-roller distributor faces backward. The angle between the multi-roller distributor and the horizontal direction is 33-46°. A circular roller feeder is set above the top of the multi-roller distributor. The direction of rotation of the circular roller feeder's rollers is opposite to the direction of rotation of each roller in the multi-roller distributor. The rotation speed of the circular rollers is 5-8 rpm. The rotation speed of each roller in the multi-roller distributor is 10-33 rpm. The moving speed of the material bed is 1.9-2.5 m / min. The sintering raw material particles obtained in step (3) are released to the multi-roller distributor through the circular roller feeder. The particle size is... Larger sintering raw material particles fall rapidly to the bottom of the material bed, while smaller particles move slowly between the rollers of the multi-roller distributor, eventually settling at the top of the material layer. This results in the following structure: the bottom layer contains 75-96 wt% sintering raw material particles with a diameter of 5-12 mm; the middle layer contains 65-90 wt% sintering raw material particles with a diameter of 3-8 mm; and the top layer contains 78-96 wt% sintering raw material particles with a diameter of less than 5 mm. The bottom layer extends from the bottom to one-third of the height of the material bed, the top layer extends from the top to one-third of the height of the material bed, and the middle layer is the area between the bottom and top layers. The thickness of the material bed is 890-960 mm. (5) Flue gas recovery and oxygen-enriched sintering; A fume hood is set above the material bed, and a mixed flue gas discharge pipe is set on the top of the fume hood. Multiple air boxes are set below the material layer. By drawing negative pressure, the gas flows from the top of the material layer down through the material layer and is discharged from the bottom of the air boxes. While the material bed moves, the material is continuously distributed in the manner of step (4). At the same time, ignition is performed to start sintering. A mixing chamber is connected to the ignition furnace. The volume content of industrial pure oxygen in the mixing chamber is set to 23-26%. Ignition is performed using oxygen-enriched gas in the mixing chamber. The ignition temperature is 1165-1180℃. At the same time, the blower is started to form a negative pressure below the material layer through multiple air boxes. The flue gas discharged from the bottom of the air box is connected to the flue gas treatment pipe and the flue gas recovery pipe respectively. The outlet end of the flue gas recovery pipe is connected to the inlet end of the mixed flue gas discharge pipe. The inlet end of the mixed flue gas discharge pipe is also connected to the oxygen discharge pipe. Oxygen and flue gas are mixed in the flue gas discharge pipe. After mixing in the pipeline, the mixture is discharged to the surface of the material bed through a fume hood; the oxygen volume content of the mixed flue gas discharged into the pipeline is set to 25-28%; flue gas is recycled and oxygen-enriched sintering is carried out to obtain sintered ore products; the oxygen content in the gas discharged into the material bed is 17-22%; an oxygen-enriched air pipeline is separately set at the rear of the material bed in the fume hood, and oxygen-enriched air is sprayed towards the material bed, the oxygen content of the oxygen-enriched air is 29-38%; a hydrogen nozzle is vertically installed through the fume hood, the hydrogen nozzle is set above the front of the material bed and behind the ignition point, the volume concentration of hydrogen is 0.52-0.91%, the sintering speed is controlled at 20.82-25.2 mm / min, the ignition point is point A, the midpoint of the material bed is point B, and the midpoint between points A and B is point C, wherein the number of hydrogen nozzles set between points A and C is 2-5 times the number set between points B and C; (6) Flue gas treatment: An electrostatic precipitator, an activated carbon desulfurization unit, a carbon monoxide catalytic oxidation device, an SCR denitrification unit, and a circulating fan are sequentially installed on the flue gas treatment pipeline. The carbon monoxide catalytic oxidation device includes an induced draft pipe, an inlet bend, a catalytic oxidation kiln, a catalytic oxidation block, an outlet bend, and a return air pipe. Both the induced draft pipe and the return air pipe are closed pipes with both ends closed. The induced draft pipe and the return air pipe are arranged parallel or approximately parallel. Both the induced draft pipe and the return air pipe are not parallel to the flue gas treatment pipeline. An inlet and an outlet are provided on the side wall of the induced draft pipe. The inlet is connected to the flue gas... The front end of the treatment pipeline is connected, the exhaust port of the induced draft pipe is connected to the inlet end of the inlet bend, the outlet end of the inlet bend is connected to the top opening of the catalytic oxidation kiln, multiple catalytic oxidation blocks are arranged inside the catalytic oxidation kiln, the bottom opening of the catalytic oxidation kiln is connected to the inlet end of the outlet bend, a catalytic gas inlet and a catalytic gas outlet are provided on the side wall of the return air pipe, the outlet end of the outlet bend is connected to the catalytic gas inlet of the return air pipe, and the catalytic gas outlet is connected to the front end of the rear section of the flue gas treatment pipeline; the end of the flue gas treatment pipeline is connected to the exhaust chimney, through which the treated flue gas is discharged.

2. The sintering method for reducing CO content in sintered ore flue gas according to claim 1, characterized in that, In step (5), the multiple bellows are divided into five bellows groups from front to back, with the direction closest to the ignition point being the front. The number of bellows in the first bellows group is 10-15% of the total number of bellows, the number of bellows in the second bellows group is 20-25%, the number of bellows in the third bellows group is 35-40%, the number of bellows in the fourth bellows group is 20-25%, and the number of bellows in the fifth bellows group is 5-9%. The flue gas discharged from the bottom of the bellows in the first, third, and fifth bellows groups is connected to the flue gas treatment pipeline, and the flue gas discharged from the bottom of the bellows in the second and fourth bellows groups is connected to the flue gas recycling pipeline. The volume ratio of the flue gas entering the flue gas treatment pipeline to the flue gas recycling pipeline is (65-75):(25-35).

3. The sintering method for reducing CO content in sintered ore flue gas according to claim 1, characterized in that, In step (5), an electrostatic precipitator and a circulating fan are installed sequentially on the flue gas recycling pipeline.

4. The sintering method for reducing CO content in sintered ore flue gas according to claim 1, characterized in that, The catalytic oxidation block in step (6) is a composite rectangular block with zirconium mullite honeycomb ceramic as the carrier and an aqueous solution of copper nitrate and cerium nitrate as the active catalytic component. Each zirconium mullite honeycomb ceramic block is provided with multiple vertically arranged through holes with a diameter of 1.5-2.5 mm and a wall thickness of 0.8-1.3 mm between the through holes. The zirconium content of the zirconium mullite honeycomb ceramic is 0.9-1.8 wt%.

5. The sintering method for reducing CO content in sintered ore flue gas according to claim 4, characterized in that, The preparation method of the catalytic oxidation block in step (6) includes the following steps: I, calcining the zircon-containing mullite honeycomb ceramic; II, preparing a composite aqueous solution of copper nitrate and cerium nitrate; III, placing the zircon-containing mullite honeycomb ceramic obtained in step I into the aqueous solution prepared in step II, setting a stirring paddle to form a vortex in the aqueous solution, setting the direction of the densely distributed through holes of the zircon-containing mullite honeycomb ceramic to face the direction of the vortex flow, and impregnating for 10-15 hours; IV, calcining the catalytic oxidation block obtained in step III.

6. The sintering method for reducing CO content in sintered ore flue gas according to claim 4 or 5, characterized in that, The preparation method of the catalytic oxidation block in step (6) includes the following steps: I. After cleaning, the zircon-containing mullite honeycomb ceramic is placed in a calcining furnace for calcination at a temperature of 380-620℃ for 0.8-2.2 hours; II. Cu is weighed according to the weight ratio of (1-6):(0.8-1.2). (NO3)2·6H2O and Ce(NO3)3·6H2O are mixed with deionized water to prepare a compound aqueous solution with a concentration of 0.38-2 mol / L; III. The zircon-containing mullite honeycomb ceramic obtained in step I is placed into the aqueous solution prepared in step II. A stirring paddle is set on the surface of the aqueous solution to form a vortex. The densely packed through holes of the zircon-containing mullite honeycomb ceramic are oriented in the direction of the vortex flow. After immersion for 10-15 hours, the catalytic oxidation block is taken out to obtain the immersion block; IV. The catalytic oxidation block obtained in step III is placed in a calcining furnace and heated to 180-280℃ in an inert gas protective atmosphere. After holding at the temperature for 3.5-5 hours, it is cooled to obtain the catalytic oxidation block product.

7. The sintering method for reducing CO content in sintered ore flue gas according to claim 1 or 4, characterized in that, The catalytic oxidation blocks are arranged in multiple layers inside the catalytic oxidation kiln, and the length and width of each layer of catalytic oxidation blocks are not equal, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane, or the catalytic oxidation blocks in each layer are staggered, so that the gaps between adjacent catalytic oxidation blocks in any layer are not in the same vertical plane; the densely packed through holes of all the catalytic oxidation blocks are respectively open to the bottom and top of the catalytic oxidation kiln.

8. The sintering method for reducing CO content in sintered ore flue gas according to claim 1 or 4, characterized in that, A support frame is provided on the material bed, and the height of the support frame is such that the top of the support frame is located at the bottom of the sintered ore layer and the top of the combustion softening layer of the material bed.

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