New process for ironmaking based on sintering-blast furnace flue gas circulation with oxygen-enriched smelting

Abstract

The application provides a sintering-blast furnace flue gas circulating iron-making new process based on oxygen-rich smelting, which comprises a sintering unit and a full-oxygen blast furnace unit for receiving oxygen-rich sintering flue gas generated by the sintering unit, the oxygen-rich sintering flue gas generated by the sintering unit enters the sintering unit and the full-oxygen blast furnace unit according to a preset ratio, and 100% circulation of the oxygen-rich sintering flue gas is realized. The configuration method of the initial configuration flue gas in the first smelting is as follows: firstly, the carbon dioxide and oxygen entering the full-oxygen blast furnace unit are calculated; secondly, the total oxygen-rich sintering flue gas amount generated by the sintering unit is calculated; and thirdly, the circulating oxygen-rich sintering flue gas amount entering the sintering unit is calculated. The application does not need to carry out desulfurization and denitrification processes, the oxygen-rich sintering flue gas is efficiently circulated through accurate calculation, the production cost of the iron-making process is reduced, and the difficult-to-handle waste generated in the oxygen-rich sintering flue gas treatment process is reduced; the top gas generated by the full-oxygen blast furnace is partially self-circulated, and the other part is used for steelmaking, so that the flue gas emission amount and the steelmaking cost are reduced.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation. Background Technology

[0002] The blast furnace ironmaking-converter steelmaking process is the main process in my country's steel production. In steel production, over 90% of the molten iron comes from blast furnace ironmaking. The ironmaking process accounts for 69.41% of the total energy consumption in steel production, with the sintering process accounting for approximately 10%-20% of the total energy consumption, making it the second largest energy-consuming process after the blast furnace. Furthermore, CO2 emissions from the ironmaking system account for over 90% of steel production emissions. Therefore, exploring low-carbon, low-energy green production technologies for iron ore sintering and blast furnace ironmaking is crucial for the green, low-carbon, and high-quality development of my country's steel industry.

[0003] Flue gas recycling is a relatively economical and feasible energy-saving and emission-reduction technology. It involves directly recycling a portion of the sintering and blast furnace flue gas. This not only reduces the amount of waste gas emitted per unit of sinter and blast furnace, but also fully utilizes the sensible heat and latent heat of CO in the flue gas. Simultaneously, some pollutants are degraded during the recycling process, reducing the amount of waste gas requiring treatment, lowering the fixed investment and operating costs of the purification system, and ultimately achieving energy conservation and emission reduction.

[0004] The current technologies for recycling sintering flue gas and blast furnace flue gas face the following challenges: (1) Recycling of sintering flue gas is limited to a portion of high-temperature, low-sulfur, high-quality sintering flue gas. A large amount of flue gas still needs to be discharged and treated by desulfurization and denitrification, which does not completely solve the problem of end-of-pipe treatment in sintering. (2) Although using sintering flue gas for blast furnace injection can effectively utilize the high-temperature environment of the blast furnace tuyeres to treat pollutants in the sintering flue gas, the amount of sintering flue gas generated is far greater than the demand of the blast furnace, and 100% treatment cannot be achieved. (3) The amount of gas generated by the recycling of top gas from an all-oxygen blast furnace is limited, and the oxygen potential content is high. The amount recycled for cooling sintered ore is insufficient, and the reduction effect is low.

[0005] Patent application number CN201811598199.7 discloses a method and apparatus for circulating sintering flue gas. This method recirculates 10%-20% of the exhaust gas from the head of the sintering machine (representing the sintering length) to the tail of the sintering machine, and recirculates 10%-20% of the exhaust gas from the tail of the sintering machine back to the head. This process requires blowing oxygen into both the head and tail of the sintering machine, while the flue gas from the middle of the sintering machine is discharged through the main flue. This process results in high oxygen consumption and low flue gas utilization.

[0006] Patent application CN201810096440.X discloses a hydrogen-rich oxygen blast furnace ironmaking method. This method involves circulating the top gas from the oxygen blast furnace into a gas upgrading furnace, converting CO2 into CO, and then introducing the upgraded gas back into the oxygen blast furnace from the middle and lower sections. Hydrogen is simultaneously introduced after the upgrading gas is introduced into the lower section, thereby improving the reduction reaction efficiency in the oxygen blast furnace and significantly reducing the amount of coke and pulverized coal used. However, this method requires the additional introduction of costly and unsafe hydrogen, making it unsuitable for large-scale use.

[0007] In view of this, it is necessary to design an improved new sintering-blast furnace flue gas recirculation ironmaking process (FOSBF) based on oxygen-enriched smelting to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to provide a new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas recycling, which solves the problems of low recycling rate of oxygen-enriched sintering flue gas, harsh recycling conditions, and high energy consumption and cost of post-processing.

[0009] To achieve the above-mentioned objectives, this invention provides a novel ironmaking process based on oxygen-enriched sintering and blast furnace flue gas circulation, comprising a sintering unit and an all-oxygen blast furnace unit for receiving the oxygen-enriched sintering flue gas generated by the sintering unit. The oxygen-enriched sintering flue gas generated by the sintering unit enters the sintering unit and the all-oxygen blast furnace unit in a preset proportion, achieving 100% circulation of the oxygen-enriched sintering flue gas; the process includes the following steps:

[0010] S1. Based on the solid fuel required for normal operation of the sintering unit, calculate the amount of oxygen required for burning the solid fuel and the amount of carbon dioxide entering the all-oxygen blast furnace unit; based on the amount of oxygen required for normal operation of the all-oxygen blast furnace unit and the amount of additional oxygen required to balance the heat lost by the carbon dioxide carbon dissolution reaction, calculate the total amount of oxygen entering the all-oxygen blast furnace unit; the sum of the amount of carbon dioxide and the total amount of oxygen is the amount of oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit.

[0011] S2. Calculate the total amount of oxygen-enriched sintering flue gas generated during normal operation of the sintering unit based on the overall industry level;

[0012] S3. Based on the difference between the total oxygen-enriched sintering flue gas volume obtained in step S2 and the blast furnace oxygen-enriched sintering flue gas volume obtained in step S1, the circulating oxygen-enriched sintering flue gas volume entering the sintering unit is obtained; based on the principle that the composition and proportion of the blast furnace oxygen-enriched sintering flue gas volume and the circulating oxygen-enriched sintering flue gas volume are equal, the oxygen content and carbon dioxide content in the circulating oxygen-enriched sintering flue gas are calculated.

[0013] S4. The sum of the amount of oxygen required for burning the solid fuel obtained in step S1, the total amount of oxygen entering the all-oxygen blast furnace unit in step S1, and the amount of oxygen in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial oxygen amount required for the first smelting; the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial carbon dioxide amount required for the first smelting.

[0014] S5. Based on the calculation results of step S4, the required amount of oxygen and carbon dioxide in the initially configured flue gas is introduced into the sintering unit for sintering-blast furnace flue gas circulation ironmaking operation; based on the amount of blast furnace oxygen-enriched sintering flue gas obtained in step S1 and the amount of circulating oxygen-enriched sintering flue gas obtained in step S3, the amount of blast furnace oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit and the amount of circulating oxygen-enriched sintering flue gas entering the sintering unit are controlled by the flow valve set at the output end of the sintering unit.

[0015] As a further improvement of the present invention, after the first smelting, subsequent smelting only requires additional oxygen to be supplied to the sintering unit.

[0016] As a further improvement of the present invention, the solid fuel in step S1 is one or more of coke powder, coal powder, and biochar.

[0017] As a further improvement of the present invention, the oxygen-enriched sintering flue gas generated by the sintering unit is removed by a dust removal system and then enters the sintering unit and the all-oxygen blast furnace unit in a preset ratio.

[0018] As a further improvement of the present invention, the sintering unit includes a sintering machine, an input unit for inputting raw materials into the sintering machine, and a circulating sintering flue gas input unit for inputting oxygen-enriched sintering flue gas into the sintering machine; the raw materials enter the sintering machine through the input unit, and the oxygen-enriched sintering flue gas generated by the sintering machine re-enters the sintering machine through the circulating sintering flue gas input unit in a preset ratio.

[0019] As a further improvement of the present invention, the raw materials include mixed iron ore powder and flux.

[0020] As a further improvement of the present invention, the input unit includes a feeder for feeding mixed iron ore powder into the sintering machine and an oxygen blower for feeding oxygen into the sintering machine.

[0021] As a further improvement of the present invention, the all-oxygen blast furnace unit includes an all-oxygen blast furnace and a blast furnace sintering flue gas input unit for receiving the oxygen-enriched sintering flue gas of the blast furnace; the oxygen-enriched sintering flue gas of the blast furnace enters the blast furnace sintering flue gas input unit from the sintering unit, and then is injected into the all-oxygen blast furnace from the tuyeres of the all-oxygen blast furnace.

[0022] As a further improvement of the present invention, it also includes a blast furnace top gas unit installed at the top of the all-oxygen blast furnace; the blast furnace top gas unit processes the top gas obtained from the all-oxygen blast furnace and inputs it into the all-oxygen blast furnace and the gas pipeline network for steel production according to a preset ratio.

[0023] As a further improvement of the present invention, the treatment process of the furnace top gas involves sequentially passing it through a gravity dust collector and a bag filter to remove dust from the furnace top gas.

[0024] The beneficial effects of this invention are:

[0025] (1) This invention provides a novel ironmaking process based on oxygen-enriched sintering and blast furnace flue gas circulation. Through precise calculations, raw materials and initial flue gas are fed in according to a preset ratio, enabling 100% circulation of the oxygen-enriched sintering flue gas generated during the sintering process, achieving zero emissions. Furthermore, the oxygen-enriched sintering flue gas can be recycled after dust removal, eliminating the need for desulfurization and denitrification processes. This not only reduces the production cost of the ironmaking process and shortens the process flow but also reduces the difficult-to-treat waste generated during the treatment of oxygen-enriched sintering flue gas, contributing to energy conservation and environmental protection.

[0026] (2) The present invention provides a new process for ironmaking based on oxygen-enriched sintering-blast furnace flue gas circulation. After the first smelting, subsequent smelting only requires additional oxygen to complete the circulation of oxygen-enriched sintering flue gas. This not only improves the smelting efficiency of ore sintering and blast furnace ironmaking, but also reduces the production cost of blast furnace ironmaking.

[0027] (3) The present invention provides a new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation, in which part of the top gas generated by the all-oxygen blast furnace is self-circulated and the other part is used for steelmaking, thereby reducing flue gas emissions and steelmaking costs.

[0028] (4) The present invention provides a new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation, which takes into account the efficient recycling of flue gas between the two different processes of iron ore sintering and blast furnace ironmaking. While meeting the smelting requirements, it eliminates the need for end-of-pipe treatment equipment for sintering flue gas, thus demonstrating low-carbon and green smelting of sintering-blast furnace. Attached Figure Description

[0029] Figure 1 This is a flowchart of the new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation, which is part of the present invention.

[0030] Figure 2 This is a flue gas circulation diagram of the new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation according to the present invention.

[0031] Figure 3 This is a diagram showing the flue gas configuration parameters and oxygen-enriched sintering flue gas distribution during the initial smelting and subsequent smelting processes in Embodiment 1 of the present invention.

[0032] Figure 4 This is a comparison chart of the cost of ultra-low emission treatment for the new ironmaking process based on oxygen-enriched sintering-blast furnace flue gas circulation of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0035] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0036] Please see Figures 1 to 2 As shown, this invention provides a novel ironmaking process based on oxygen-enriched sintering and blast furnace flue gas circulation, comprising a sintering unit and an all-oxygen blast furnace unit for receiving the oxygen-enriched sintering flue gas generated by the sintering unit. The oxygen-enriched sintering flue gas generated by the sintering unit enters the sintering unit and the all-oxygen blast furnace unit according to a preset ratio, achieving 100% circulation of the oxygen-enriched sintering flue gas; including the following steps:

[0037] S1. Based on the solid fuel required for normal operation of the sintering unit, calculate the amount of oxygen required for burning the solid fuel and the amount of carbon dioxide entering the all-oxygen blast furnace unit; based on the amount of oxygen required for normal operation of the all-oxygen blast furnace unit and the amount of additional oxygen required to balance the heat lost by carbon dioxide in the carbon dissolution reaction, calculate the total amount of oxygen entering the all-oxygen blast furnace unit; the sum of the amount of carbon dioxide and the total amount of oxygen is the amount of oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit; wherein, the solid fuel is one or more of coke powder, coal powder, and biochar.

[0038] S2. Calculate the total amount of oxygen-enriched sintering flue gas generated during normal operation of the sintering unit based on the overall industry level.

[0039] S3. Based on the difference between the total oxygen-enriched sintering flue gas volume obtained in step S2 and the blast furnace oxygen-enriched sintering flue gas volume obtained in step S1, the circulating oxygen-enriched sintering flue gas volume entering the sintering unit is obtained; based on the principle that the composition and proportion of the blast furnace oxygen-enriched sintering flue gas volume and the circulating oxygen-enriched sintering flue gas volume are equal, the oxygen content and carbon dioxide content in the circulating oxygen-enriched sintering flue gas are calculated.

[0040] S4. The sum of the amount of oxygen required for burning solid fuel obtained in step S1, the total amount of oxygen entering the all-oxygen blast furnace unit in step S1, and the amount of oxygen in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial oxygen amount required for the first smelting; the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial carbon dioxide amount required for the first smelting.

[0041] S5. Based on the calculation results of step S4, the required amount of oxygen and carbon dioxide in the initially configured flue gas is introduced into the sintering unit for sintering-blast furnace flue gas circulation ironmaking operation; based on the amount of blast furnace oxygen-enriched sintering flue gas obtained in step S1 and the amount of circulating oxygen-enriched sintering flue gas obtained in step S3, the amount of blast furnace oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit and the amount of circulating oxygen-enriched sintering flue gas entering the sintering unit are controlled by the flow valve set at the output end of the sintering unit.

[0042] (The oxygen-enriched sintering flue gas generated in the sintering unit is called the total oxygen-enriched sintering flue gas, the oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit is called the blast furnace oxygen-enriched sintering flue gas, and the oxygen-enriched sintering flue gas that re-enters the sintering unit is called the circulating oxygen-enriched sintering flue gas.)

[0043] The sintering unit includes a sintering machine, an input unit for feeding raw materials (including mixed iron ore powder and flux) into the sintering machine, and a circulating sintering flue gas input unit for circulating oxygen-enriched sintering flue gas into the sintering machine. The raw materials enter the sintering machine through the input unit, and the total oxygen-enriched sintering flue gas generated by the sintering machine re-enters the sintering machine through the circulating sintering flue gas input unit according to a preset ratio.

[0044] In some embodiments, the input unit includes a feeder and an oxygen blower for feeding raw materials into the sintering machine; the raw materials entering the sintering machine from the input end include mixed iron ore powder, flux, coke powder, and oxygen. The mixed iron ore powder, flux, and coke powder are fed into the sintering machine from the feeder, while the oxygen is fed into the sintering machine from the oxygen blower. (The coke powder, as fuel, generates a large amount of heat during combustion with oxygen, causing the mixed iron ore powder in the material layer to become molten. As the combustion layer moves downward and cold air passes through, the generated molten liquid phase cools, crystallizes, and solidifies into a porous sinter with stable chemical composition and physical properties, making the subsequent blast furnace smelting process more efficient.)

[0045] During the initial smelting, no circulating oxygen-enriched smelting flue gas enters the sintering machine from the circulating sintering flue gas input unit. Instead, an initial configuration of flue gas (a mixture of oxygen and carbon dioxide in a preset ratio) is directly introduced into the sintering machine based on precise calculations. After the initial smelting, subsequent smelting only requires additional oxygen to be introduced into the sintering machine via an oxygen blower.

[0046] The total oxygen-enriched sintering flue gas generated by the sintering machine is collected by the lower fume hood and sent to the main flue. After being removed by the dust removal system, it is controlled by a flow valve set at the output end of the sintering machine according to a preset ratio. A portion of the oxygen-enriched sintering flue gas is used as sintering combustion gas and re-enters the sintering machine through the circulating sintering flue gas input unit, which is the circulating oxygen-enriched sintering flue gas. The other portion of the oxygen-enriched sintering flue gas enters the all-oxygen blast furnace unit through the blast furnace sintering flue gas input unit, which is the blast furnace oxygen-enriched sintering flue gas.

[0047] The all-oxygen blast furnace unit includes an all-oxygen blast furnace and a blast furnace sintering flue gas input unit for receiving oxygen-enriched sintering flue gas generated by the sintering unit; the oxygen-enriched sintering flue gas enters the blast furnace flue gas input unit from the sintering unit, and then is injected into the all-oxygen blast furnace from the tuyeres.

[0048] Specifically, the blast furnace sintering flue gas input unit includes a blast furnace blast pipe and several branch pipes connected to the blast furnace blast pipe. The oxygen-enriched blast furnace sintering flue gas is sent from the several branch pipes to several tuyeres of the all-oxygen blast furnace and injected into the all-oxygen blast furnace.

[0049] This invention provides a novel sintering-blast furnace flue gas recycling ironmaking process based on oxygen-enriched smelting, and further includes a blast furnace top gas unit located at the top of an all-oxygen blast furnace. The blast furnace top gas unit first passes the top gas from the all-oxygen blast furnace through a gravity dust collector and then through a bag filter to remove dust. A portion of the dust-removed gas is heated by a gas heater and then injected into the all-oxygen blast furnace through the furnace body (the input amount of this portion of gas depends on the composition of the top gas and the smelting state of the all-oxygen blast furnace; the heating temperature of the gas also depends on the smelting state of the all-oxygen blast furnace). The remaining gas is used as external flue gas for steel production through a gas pipeline network.

[0050] During the initial smelting, the preparation method for the raw materials (mixed iron ore powder, flux, and coke powder) and the initial flue gas (oxygen and carbon dioxide) is as follows: First, calculate the amount of carbon dioxide and oxygen entering the all-oxygen blast furnace unit, i.e., the blast furnace sintering flue gas volume; then calculate the total oxygen-enriched sintering flue gas volume generated by the sintering unit; next, calculate the circulating oxygen-enriched sintering flue gas volume entering the sintering unit; finally, based on the calculation results, add the mixed iron ore powder, flux, coke powder, oxygen, and carbon dioxide to the sintering unit. The specific calculation steps are as follows: (The total iron grade of the sintered ore is known to be ω (%).

[0051] S1. Based on the carbon content a (kg) in the solid fuel required for normal operation of the sintering unit (referring to the amount that can be calculated based on the sintering raw materials and sintering process, combined with the theories of chemical equilibrium and mass conservation when sintering is carried out alone, a in this application can be obtained directly from known quantities in the industry), the amount of oxygen consumed b (mol) and the amount of carbon dioxide produced c (mol) per ton of molten iron produced by the sintering unit are calculated: b = c = (a × 1000) / (12 × ω), that is, the amount of carbon dioxide entering the all-oxygen blast furnace unit is c (mol); (the calculation basis is C + O2 = CO2).

[0052] Based on the energy and mass balance model of the all-oxygen blast furnace, the amount of oxygen d (mol) required at the tuyeres when the sintered ore produced by the sintering unit is input into the all-oxygen blast furnace during normal operation is calculated (this value is known in the industry, and only unit conversion is required).

[0053] Based on the principle of equal heat, the amount of oxygen required to supplement the sintering unit when the carbon dioxide c (mol) is introduced into the all-oxygen blast furnace is calculated as e (mol): e = 0.688 × c;

[0054] That is, the total amount of oxygen entering the all-oxygen blast furnace unit is e+d (mol);

[0055] (When carbon dioxide from the oxygen-enriched sintering flue gas enters the all-oxygen blast furnace, a carbon dissolution reaction occurs, which is endothermic; therefore, additional oxygen is needed. The supplemented oxygen undergoes incomplete combustion with the carbon at the tuyeres to produce carbon monoxide, which is exothermic; it is necessary to ensure that the heat absorbed and the heat released are equal.)

[0056] C+CO2=CO; ΔH=-172.74kJ / mol

[0057] 2C + O₂ = 2CO; ΔH = 250 kJ / mol

[0058] As shown in the above reaction formula, 1 mol of carbon dioxide requires 172.74 kJ / mol of heat to undergo a carbon dissolution reaction, while 1 mol of oxygen releases 250 kJ / mol of heat when burning carbon to produce carbon monoxide. The ratio of carbon dioxide to oxygen is 1:0.688. Therefore, to ensure the heat balance in the tuyeres of an oxygen-enriched blast furnace, an additional 0.668 mol of oxygen is needed to introduce 1 mol of carbon dioxide into the oxygen-enriched sintering flue gas.

[0059] As can be seen from step S1, the total amount of oxygen-enriched sintering flue gas fed into the all-oxygen blast furnace unit is f (mol): f = c + e + d, where the amount of carbon dioxide is c (mol) and the amount of oxygen is e + d (mol).

[0060] (The total amount of oxygen-enriched sintering flue gas in a blast furnace is the sum of the amount of carbon dioxide generated by the combustion of solid fuel in the sintering unit, the amount of oxygen required for normal operation of the all-oxygen blast furnace unit, and the amount of oxygen required to balance the heat of the all-oxygen blast furnace unit.)

[0061] S2. Based on the overall industry level, the total oxygen-enriched sintering flue gas volume V (m³) generated during normal operation of the sintering unit is known. 3 / t), calculate the total amount of oxygen-enriched sintering flue gas required to produce one ton of molten iron in the sintering unit, g (mol): g=(1000×V) / (22.4×ω);

[0062] S3. According to the principle of material balance of oxygen-enriched sintering flue gas, the total amount of oxygen-enriched sintering flue gas obtained in step S2 is g (mol), and the amount of blast furnace oxygen-enriched sintering flue gas obtained in step S1 is f (mol). Therefore, the amount of circulating oxygen-enriched sintering flue gas entering the sintering unit is h (mol): h = gf.

[0063] Based on the principle that the composition and proportion of each component are the same in both the circulating oxygen-enriched sintering flue gas and the blast furnace oxygen-enriched sintering flue gas, the carbon dioxide content i (mol) in the circulating oxygen-enriched sintering flue gas is calculated as: i = h × c / f, and the oxygen content j (mol) is calculated as: j = hi.

[0064] The composition and content of the circulating oxygen-enriched sintering flue gas are: carbon dioxide h×c / f (mol), oxygen hi (mol).

[0065] S4. Based on the oxygen quantity b (mol) required for burning solid fuel obtained in step S1, the total oxygen quantity e+d (mol) entering the all-oxygen blast furnace unit in step S1, and the oxygen quantity hi (mol) in the circulating oxygen-enriched sintering flue gas obtained in step S3, calculate the initial oxygen quantity n required in the flue gas for the first smelting. O2 (mol): n O2 =b + e + d + hi;

[0066] Based on the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas obtained in step S3, calculate the amount of carbon dioxide n required in the initial flue gas configuration for the first smelting. CO2 (mol): n CO2 =h×c / f;

[0067] The initial flue gas configuration parameters required for the first smelting are as follows:

[0068] oxygen quantity n O2 (mol): n O2 =b + e + d + hi;

[0069] carbon dioxide amount n CO2 (mol): n CO2=h×c / f;

[0070] The amount of additional oxygen needed for each subsequent normal smelting process is b + d + e (mol);

[0071] Based on the energy and mass balance model of an all-oxygen blast furnace, the circulation volume of the upper flue gas and the external gas supply volume can be calculated.

[0072] The present invention will now be described in detail through specific embodiments:

[0073] Example 1

[0074] In 2018, the average amount of oxygen-enriched sintering flue gas generated per ton of sinter produced in the entire industry (i.e., the total amount of oxygen-enriched sintering flue gas) was 2500 m³. 3 / t, with an average cooling oxygen-enriched sintering flue gas volume of 2200 m³ / t. 3 / t, the iron grade of the iron ore used in the production of sinter in the whole industry is 55%, and the solid fuel coke powder used in the production process of each ton of sinter is 54kg (the coke powder has a carbon content of 90%).

[0075] The specific steps for calculating the flue gas configuration parameters during sintering are as follows:

[0076] S1. The carbon content in the coke powder consumed by the sintering unit per ton of molten iron is calculated as: (54×1000×90%) / (12×55%)=7360mol;

[0077] According to C+O2=CO2, this sintering unit needs to consume 7360mol of oxygen and generate 7360mol of carbon dioxide, that is, the amount of carbon dioxide entering the all-oxygen blast furnace unit is 7360mol.

[0078] Based on actual smelting needs, the oxygen consumption per ton of molten iron during normal operation of an all-oxygen blast furnace is calculated to be 274 m³. 3 That is, the amount of oxygen required for normal production is: 274 × 1000 / 22.4 = 12230 mol;

[0079] According to the principle of heat balance, the 7360mol of carbon dioxide generated by the combustion of solid fuel in the sintering unit enters the oxygen-rich blast furnace, and the amount of oxygen that needs to be added is: 7360mol × 0.688 = 5070mol.

[0080] That is, the total amount of oxygen entering the all-oxygen blast furnace unit is: 12230 + 5070 = 17300 mol;

[0081] Therefore, the amount of oxygen-enriched sintering flue gas fed into the all-oxygen blast furnace is: 7360 + 5070 + 12230 = 24660 mol, of which the components and contents are: carbon dioxide 7360 mol and oxygen 17300 mol.

[0082] The composition and content of the oxygen-enriched sintering flue gas from the blast furnace are: 7360 mol of carbon dioxide and 17300 mol of oxygen.

[0083] S2. The total amount of oxygen-enriched sintering flue gas generated by the sintering unit per ton of molten iron is calculated as: (1000×2500) / (22.4×55%)=202920mol;

[0084] S3. Based on the total oxygen-enriched sintering flue gas volume generated in step S2 being 202920mol and the blast furnace oxygen-enriched sintering flue gas volume generated in step S1 being 24660mol, the circulating oxygen-enriched sintering flue gas volume entering the sintering machine through the circulating flue gas input unit is calculated to be: 202920mol-24660=178260mol.

[0085] Based on the principle that the composition and proportion of each component are the same in the circulating oxygen-enriched sintering flue gas input from the circulating flue gas input unit and the blast furnace oxygen-enriched sintering flue gas input from the blast furnace flue gas input unit, the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas is calculated to be: 7360×178260 / 24660=53200mol, and the amount of oxygen is 178260-53200=125060mol;

[0086] The composition and content of the circulating oxygen-enriched sintering flue gas are: 53,200 mol of carbon dioxide and 125,060 mol of oxygen.

[0087] S4. Based on the above calculations, the parameters of the initial flue gas configuration during sintering can be obtained: (e.g.) Figure 3 (As shown)

[0088] Assuming that 7360 mol of carbon is burned per ton of sinter, the initial flue gas configuration for the first smelting is a mixture of oxygen and carbon dioxide, with 149720 mol of oxygen and 53200 mol of carbon dioxide.

[0089] (Based on the oxygen amount of 7360mol required for burning solid fuel obtained in step S1, the total oxygen amount of 17300mol entering the all-oxygen blast furnace unit in step S1, and the oxygen amount of 125060mol in the circulating oxygen-enriched sintering flue gas obtained in step S3, the initial oxygen amount required for the first smelting is calculated to be 7360+5070+125060=149720mol)

[0090] (Based on the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas obtained in step S3, the amount of carbon dioxide in the initial flue gas required for the first smelting is calculated to be 53200 mol.)

[0091] Each subsequent normal smelting process only requires an additional 24,660 mol of oxygen, with the remaining gas being 178,260 mol of circulating oxygen-enriched sintering flue gas.

[0092] like Figure 4 The chart showing a cost comparison between the new sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting and ultra-low emission treatment is presented. The total cost per ton of ore for the process of this invention is RMB 151.91 (sintering cost RMB 45.34, blast furnace cost RMB 106.57), while the total cost per ton of ore for traditional ultra-low emission treatment is RMB 172.78 (internal cost per ton of ore RMB 34.63, external cost per ton of ore RMB 138.15). The new sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting can reduce the infrastructure and operation investment and by-product treatment costs associated with desulfurization and denitrification, while also contributing to synergistic emission reduction and energy conservation in the sintering and blast furnace processes, demonstrating significant cost advantages. (Data source: Research on Environmental and Economic Impact Assessment of Ultra-Low Emission Treatment Technology for Iron and Steel Sintering Flue Gas Based on Life Cycle Theory)

[0093] In summary, this invention provides a novel ironmaking process based on oxygen-enriched sintering and blast furnace flue gas circulation. Through precise calculations, raw materials and initial flue gas are input according to a preset ratio, enabling 100% circulation of the oxygen-enriched sintering flue gas generated during the sintering process, achieving zero emissions. Furthermore, the oxygen-enriched sintering flue gas can be recycled after dust removal, eliminating the need for desulfurization and denitrification processes. This not only reduces the production cost of ironmaking and shortens the process flow but also reduces the difficult-to-treat waste generated during the oxygen-enriched sintering flue gas treatment process, contributing to energy conservation and environmental protection. A portion of the top gas generated by the all-oxygen blast furnace is self-circulated, while the other portion is used for steelmaking, reducing flue gas emissions and steelmaking costs. By comprehensively considering the efficient recycling of flue gas between the two different processes of iron ore sintering and blast furnace ironmaking, this process meets smelting requirements while eliminating the need for end-of-pipe treatment equipment for sintering flue gas, demonstrating low-carbon and green smelting through sintering and blast furnace processes.

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting, characterized in that: The system includes a sintering unit and an oxygen-rich blast furnace unit for receiving the oxygen-rich sintering flue gas generated by the sintering unit. The oxygen-rich sintering flue gas generated by the sintering unit enters the sintering unit and the oxygen-rich blast furnace unit according to a preset ratio, achieving 100% circulation of the oxygen-rich sintering flue gas. The system includes the following steps: S1. Based on the solid fuel required for normal operation of the sintering unit, calculate the amount of oxygen required for burning the solid fuel and the amount of carbon dioxide entering the all-oxygen blast furnace unit; based on the amount of oxygen required for normal operation of the all-oxygen blast furnace unit and the amount of additional oxygen required to balance the heat lost by the carbon dioxide carbon dissolution reaction, calculate the total amount of oxygen entering the all-oxygen blast furnace unit; the sum of the amount of carbon dioxide and the total amount of oxygen is the amount of oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit. S2. Calculate the total amount of oxygen-enriched sintering flue gas generated during normal operation of the sintering unit based on the overall industry level; S3. Based on the difference between the total oxygen-enriched sintering flue gas volume obtained in step S2 and the blast furnace oxygen-enriched sintering flue gas volume obtained in step S1, the circulating oxygen-enriched sintering flue gas volume entering the sintering unit is obtained; based on the principle that the composition and proportion of the blast furnace oxygen-enriched sintering flue gas volume and the circulating oxygen-enriched sintering flue gas volume are equal, the oxygen content and carbon dioxide content in the circulating oxygen-enriched sintering flue gas are calculated. S4. The sum of the amount of oxygen required for burning the solid fuel obtained in step S1, the total amount of oxygen entering the all-oxygen blast furnace unit in step S1, and the amount of oxygen in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial oxygen amount required for the first smelting; the amount of carbon dioxide in the circulating oxygen-enriched sintering flue gas obtained in step S3 shall be used as the initial carbon dioxide amount required for the first smelting. S5. Based on the calculation results of step S4, the required amount of oxygen and carbon dioxide in the initially configured flue gas is introduced into the sintering unit for sintering-blast furnace flue gas circulation ironmaking operation; based on the amount of blast furnace oxygen-enriched sintering flue gas obtained in step S1 and the amount of circulating oxygen-enriched sintering flue gas obtained in step S3, the amount of blast furnace oxygen-enriched sintering flue gas entering the all-oxygen blast furnace unit and the amount of circulating oxygen-enriched sintering flue gas entering the sintering unit are controlled by the flow valve set at the output end of the sintering unit.

2. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 1, characterized in that: After the initial smelting, subsequent smelting only requires additional oxygen to be supplied to the sintering unit.

3. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 1, characterized in that: The solid fuel mentioned in step S1 is one or more of coke powder, coal powder, and biochar.

4. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 1, characterized in that: The oxygen-enriched sintering flue gas generated by the sintering unit is removed by a dust removal system and then enters the sintering unit and the all-oxygen blast furnace unit according to a preset ratio.

5. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 4, characterized in that: The sintering unit includes a sintering machine, an input unit for inputting raw materials into the sintering machine, and a circulating sintering flue gas input unit for inputting oxygen-enriched sintering flue gas into the sintering machine. The raw materials enter the sintering machine through the input unit, and the oxygen-enriched sintering flue gas generated by the sintering machine re-enters the sintering machine through the circulating sintering flue gas input unit in a preset ratio.

6. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 5, characterized in that: The raw materials include mixed iron ore powder and flux.

7. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 6, characterized in that: The input unit includes a feeder for feeding mixed iron ore powder into the sintering machine and an oxygen blower for feeding oxygen into the sintering machine.

8. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 1, characterized in that: The all-oxygen blast furnace unit includes an all-oxygen blast furnace and a blast furnace sintering flue gas input unit for receiving the oxygen-enriched sintering flue gas from the blast furnace; the oxygen-enriched sintering flue gas enters the blast furnace sintering flue gas input unit from the sintering unit, and is then injected into the all-oxygen blast furnace from the tuyeres.

9. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 1, characterized in that: It also includes a blast furnace top gas unit installed at the top of the all-oxygen blast furnace; the blast furnace top gas unit processes the top gas obtained from the all-oxygen blast furnace and inputs it into the all-oxygen blast furnace and the gas pipeline network used for steel production according to a preset ratio.

10. The sintering-blast furnace flue gas recirculation ironmaking process based on oxygen-enriched smelting according to claim 9, characterized in that: The process of treating the top gas involves passing it through a gravity dust collector and a bag filter in sequence to remove dust from the top gas.

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